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  • Figure 4.0 Bacteria on human skin cells
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • Figure 4.1 Types of micrographs
  • Figure 4.1a Types of micrographs (LM)
  • Figure 4.1b Types of micrographs (SEM)
  • Figure 4.1c Types of micrographs (TEM)
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • Figure 4.2 Electron microscope
  • Figure 4.3 The size range of cells
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • Figure 4.4 An idealized prokaryotic cell
  • Figure 4.4a Prokaryotic cell: art
  • Figure 4.4b Prokaryotic cell: TEM
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • <number>
    Student Misconceptions and Concerns
    1. Students typically cannot distinguish between resolution and magnification. However, pixels and resolution of digital images can help clarify the distinction. Consider printing the same image at high and low resolution or enlarging the same image at two different levels of resolution. Teaching tip #2 below suggests another related exercise.
    2. Students frequently equate the functions of mitochondria and chloroplasts as alternate ways to acquire usable energy. This often leads to the conclusion that animal cells have mitochondria but not chloroplasts and that plant cells have chloroplasts but not mitochondria. Plant cells have both.
    Teaching Tips
    1. Here is a chance to challenge students to identify technology that has extended our senses. Chemical probes can identify what we cannot taste, listening devices detect what we do not normally hear, night vision and ultraviolet (UV) cameras detect or magnify wavelengths beyond our vision, etc. Students could be assigned the task of preparing a short report on one of these technologies.
    2. Here is a way to demonstrate resolving power in the classroom. Use a marker and your classroom marker board to make several pairs of dots separated by shorter and shorter distances. Start out with two dots clearly separated apart—perhaps by 4–5 cm—and end with a pair of dots that touch. Label them a, b, c, etc. Ask your students to indicate the letters of the pairs of points that they can distinguish as separate; this is the definition of resolution for their eyes. (They need not state their answers publicly, to avoid embarrassment.)
    3. Most biology laboratories have two types of microscopes for student use: a dissection (or stereo-) microscope and a compound light microscope using microscope slides. The way these scopes function parallels the workings of EMs. Dissection microscopes are like a SEM—both rely upon a beam reflected off a surface. As you explain this to your class, hold up an object, identify a light source in the room, and explain that our eyes see most images when our eyes detect light that has reflected off the surface of an object. Compound light microscopes are like TEMs, in which a beam is transmitted through a thin sheet of material. If you have an overhead or other strong light source, hold up a piece of paper between your eye and the light source. You will see the internal detail of the paper as light is transmitted through the paper to your eye . . . the way a compound light microscope or TEM works!
    4. Even in college, students still struggle with the metric system. When discussing the scale of life, consider bringing a meter stick to class. The relationship between a meter and a millimeter is the same as a millimeter is to a micron. Each is a difference of 1000.
    5. This is a place where a visual image comparing a prokaryotic and eukaryotic cell can be very helpful. These cells are strikingly different in size and composition. A visual reference point instead of just abstract ideas and traits will be a continual reminder for your students during your discussion of these cells.
    6. Students might wrongly conclude that prokaryotes are typically one-tenth the volume of eukaryotic cells. A difference in diameter by a factor of ten translates into a much greater difference in volume. Students might be challenged to recall enough geometry to calculate the difference in the volume of two cells with diameters that differ by a factor of ten.
    7. Germs—here is a term that we learn early in our lives but that is rarely well defined. Students may appreciate a biological explanation. The general use of germs is a reference to anything that causes disease. This may be a good time to sort the major disease-causing agents into three categories: (1) bacteria (prokaryotes), (2) viruses (not yet addressed), and (3) single-celled and multicellular eukaryotes (athlete’s foot is a fungal infection; malaria is caused by a unicellular eukaryote).
    8. Some instructors have reported great success by challenging their students to make analogies to the functions of the many organelles discussed below. Students may wish to construct one inclusive analogy between a society or factory (used in the text) and a cell or to construct separate analogies for each organelle. As with any analogy, it is important to list the similarities and differences/exceptions.
    9. This might be a good time to discuss the evolution of antibiotic resistance. Teaching tips and ideas for related lessons can be found at http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html.
  • Figure 4.5 A view of an idealized animal cell and plant cell
  • Figure 4.5a A view of an idealized animal cell
  • Figure 4.5b A view of an idealized plant cell
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Figure 4.6 Plasma membrane structure
  • <number>
    Figure 4.6a Phospholipid bilayer of membrane
  • <number>
    Figure 4.6b Fluid mosaic model of membrane
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • Figure 4.7 How MRSA may destroy human immune cells (Step 1)
  • Figure 4.7 How MRSA may destroy human immune cells (Step 2)
  • Figure 4.7 How MRSA may destroy human immune cells (Step 3)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Students often think of the function of cell membranes as mainly containment, like that of a plastic bag. Consider relating the functions of membranes to our human skin. (For example, both membranes and our skin detect stimuli, engage in gas exchange, and serve as sites of excretion and absorption.)
    Teaching Tips
    1. The hydrophobic and hydrophilic ends of a phospholipid molecule naturally create a lipid bilayer. The hydrophobic edges of the layer will seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell). Further, because of these hydrophobic properties, lipid bilayers are naturally self-healing. That all of this organization naturally emerges from the properties of phospholipids is worth sharing with your students.
    2. You might wish to share a very simple analogy that seems to work with some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy to find exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
  • <number>
    Student Misconceptions and Concerns
    1. Noting the main flow of genetic information from DNA to RNA to Protein on the board will provide a useful reference for students when explaining these processes. As a review, have students note where new molecules of DNA, RNA, and proteins are produced in a cell.
    2. Consider challenging your students to explain how we can have four main types of organic molecules functioning in specific roles in our cells, yet DNA and RNA only specifically dictate the generation of proteins (and more copies of DNA and RNA). How is the production of specific types of carbohydrates and lipids in cells controlled? (Answer: primarily by the specific properties of enzymes.)
    Teaching Tips
    Some of your more knowledgeable students may like to guess the exceptions to 46 chromosomes per human cell. These exceptions include gametes, some of the cells that produce them, and red blood cells in non-fetal mammals.
    2. If you wish to continue the text’s factory analogy, nuclear pores might be said to function most like the doors to the boss’s office.
    3. If you want to challenge your students further, ask them to consider the adaptive advantage of using mRNA to direct the production of proteins instead of using DNA directly. Some biologists suggest that DNA is better protected in the nucleus and that mRNA, exposed to more damaging cross-reactions in the cytosol, is the temporary working copy of the genetic material. In some ways, this is similar to making a working photocopy of an important document, keeping the original copy safely stored away.
  • <number>
    Student Misconceptions and Concerns
    1. Noting the main flow of genetic information from DNA to RNA to Protein on the board will provide a useful reference for students when explaining these processes. As a review, have students note where new molecules of DNA, RNA, and proteins are produced in a cell.
    2. Consider challenging your students to explain how we can have four main types of organic molecules functioning in specific roles in our cells, yet DNA and RNA only specifically dictate the generation of proteins (and more copies of DNA and RNA). How is the production of specific types of carbohydrates and lipids in cells controlled? (Answer: primarily by the specific properties of enzymes.)
    Teaching Tips
    Some of your more knowledgeable students may like to guess the exceptions to 46 chromosomes per human cell. These exceptions include gametes, some of the cells that produce them, and red blood cells in non-fetal mammals.
    2. If you wish to continue the text’s factory analogy, nuclear pores might be said to function most like the doors to the boss’s office.
    3. If you want to challenge your students further, ask them to consider the adaptive advantage of using mRNA to direct the production of proteins instead of using DNA directly. Some biologists suggest that DNA is better protected in the nucleus and that mRNA, exposed to more damaging cross-reactions in the cytosol, is the temporary working copy of the genetic material. In some ways, this is similar to making a working photocopy of an important document, keeping the original copy safely stored away.
  • Figure 4.8 The nucleus
  • Figure 4.8a The nucleus: art
  • Figure 4.8b Nuclear envelope
  • Figure 4.8c Nuclear pores
  • <number>
    Student Misconceptions and Concerns
    1. Noting the main flow of genetic information from DNA to RNA to Protein on the board will provide a useful reference for students when explaining these processes. As a review, have students note where new molecules of DNA, RNA, and proteins are produced in a cell.
    2. Consider challenging your students to explain how we can have four main types of organic molecules functioning in specific roles in our cells, yet DNA and RNA only specifically dictate the generation of proteins (and more copies of DNA and RNA). How is the production of specific types of carbohydrates and lipids in cells controlled? (Answer: primarily by the specific properties of enzymes.)
    Teaching Tips
    Some of your more knowledgeable students may like to guess the exceptions to 46 chromosomes per human cell. These exceptions include gametes, some of the cells that produce them, and red blood cells in non-fetal mammals.
    2. If you wish to continue the text’s factory analogy, nuclear pores might be said to function most like the doors to the boss’s office.
    3. If you want to challenge your students further, ask them to consider the adaptive advantage of using mRNA to direct the production of proteins instead of using DNA directly. Some biologists suggest that DNA is better protected in the nucleus and that mRNA, exposed to more damaging cross-reactions in the cytosol, is the temporary working copy of the genetic material. In some ways, this is similar to making a working photocopy of an important document, keeping the original copy safely stored away.
  • Figure 4.9 The relationship between DNA, chromatin, and a chromosome
  • <number>
    Student Misconceptions and Concerns
    1. Noting the main flow of genetic information from DNA to RNA to Protein on the board will provide a useful reference for students when explaining these processes. As a review, have students note where new molecules of DNA, RNA, and proteins are produced in a cell.
    2. Consider challenging your students to explain how we can have four main types of organic molecules functioning in specific roles in our cells, yet DNA and RNA only specifically dictate the generation of proteins (and more copies of DNA and RNA). How is the production of specific types of carbohydrates and lipids in cells controlled? (Answer: primarily by the specific properties of enzymes.)
    Teaching Tips
    Some of your more knowledgeable students may like to guess the exceptions to 46 chromosomes per human cell. These exceptions include gametes, some of the cells that produce them, and red blood cells in non-fetal mammals.
    2. If you wish to continue the text’s factory analogy, nuclear pores might be said to function most like the doors to the boss’s office.
    3. If you want to challenge your students further, ask them to consider the adaptive advantage of using mRNA to direct the production of proteins instead of using DNA directly. Some biologists suggest that DNA is better protected in the nucleus and that mRNA, exposed to more damaging cross-reactions in the cytosol, is the temporary working copy of the genetic material. In some ways, this is similar to making a working photocopy of an important document, keeping the original copy safely stored away.
  • Figure 4.10 Computer model of a ribosome synthesizing a protein
  • <number>
    Student Misconceptions and Concerns
    1. Noting the main flow of genetic information from DNA to RNA to Protein on the board will provide a useful reference for students when explaining these processes. As a review, have students note where new molecules of DNA, RNA, and proteins are produced in a cell.
    2. Consider challenging your students to explain how we can have four main types of organic molecules functioning in specific roles in our cells, yet DNA and RNA only specifically dictate the generation of proteins (and more copies of DNA and RNA). How is the production of specific types of carbohydrates and lipids in cells controlled? (Answer: primarily by the specific properties of enzymes.)
    Teaching Tips
    Some of your more knowledgeable students may like to guess the exceptions to 46 chromosomes per human cell. These exceptions include gametes, some of the cells that produce them, and red blood cells in non-fetal mammals.
    2. If you wish to continue the text’s factory analogy, nuclear pores might be said to function most like the doors to the boss’s office.
    3. If you want to challenge your students further, ask them to consider the adaptive advantage of using mRNA to direct the production of proteins instead of using DNA directly. Some biologists suggest that DNA is better protected in the nucleus and that mRNA, exposed to more damaging cross-reactions in the cytosol, is the temporary working copy of the genetic material. In some ways, this is similar to making a working photocopy of an important document, keeping the original copy safely stored away.
  • Figure 4.11 Locations of ribosomes
  • <number>
    Student Misconceptions and Concerns
    1. Noting the main flow of genetic information from DNA to RNA to Protein on the board will provide a useful reference for students when explaining these processes. As a review, have students note where new molecules of DNA, RNA, and proteins are produced in a cell.
    2. Consider challenging your students to explain how we can have four main types of organic molecules functioning in specific roles in our cells, yet DNA and RNA only specifically dictate the generation of proteins (and more copies of DNA and RNA). How is the production of specific types of carbohydrates and lipids in cells controlled? (Answer: primarily by the specific properties of enzymes.)
    Teaching Tips
    Some of your more knowledgeable students may like to guess the exceptions to 46 chromosomes per human cell. These exceptions include gametes, some of the cells that produce them, and red blood cells in non-fetal mammals.
    2. If you wish to continue the text’s factory analogy, nuclear pores might be said to function most like the doors to the boss’s office.
    3. If you want to challenge your students further, ask them to consider the adaptive advantage of using mRNA to direct the production of proteins instead of using DNA directly. Some biologists suggest that DNA is better protected in the nucleus and that mRNA, exposed to more damaging cross-reactions in the cytosol, is the temporary working copy of the genetic material. In some ways, this is similar to making a working photocopy of an important document, keeping the original copy safely stored away.
  • Figure 4.12 DNA → RNA → Protein (Step 1)
  • Figure 4.12 DNA → RNA → Protein (Step 2)
  • Figure 4.12 DNA → RNA → Protein (Step 3)
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • Figure 4.13 Endoplasmic reticulum (ER)
  • Figure 4.13a Endoplasmic reticulum (ER) art
  • Figure 4.13b Endoplasmic reticulum (ER) TEM
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • Figure 4.14 How rough ER manufactures and packages secretory proteins
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • Figure 4.15 The Golgi apparatus
  • Figure 4.15a The Golgi apparatus art
  • Figure 4.15b The Golgi apparatus SEM
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • Figure 4.16 Two functions of lysosomes
  • Figure 4.16a Lysosome digesting food
  • Figure 4.16b Lysosome breaking down the molecules of damaged organelles
  • Figure 4.16c Lysosome micrograph
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • Figure 4.17 Two types of vacuoles
  • Figure 4.17a Contractile vacuole in Paramecium
  • Figure 4.17b Central vacuole in a plant cell
  • <number>
    Student Misconceptions and Concerns
    1. Students might have trouble connecting the diverse functions to the organelles. The pathway of secretory proteins is a good process to use to introduce the primary organelle functions. The movement of information and products extends generally from the central nucleus to the interconnected rough ER, to the more peripherally located Golgi, and finally to the outer plasma membrane. Introducing the steps of this process with the central to peripheral flow may help students better see the interrelationships and recall the sequence.
    2. Conceptually, some students seem to benefit from the well-developed factory-like-a-cell analogy developed in the text. The use of this analogy in lecture might help to anchor these relationships.
    Teaching Tips
    1. The endoplasmic reticulum is continuous with the outer nuclear membrane. This explains why the ER is usually found close to the nucleus.
    2. Some people think the Golgi apparatus looks like a stack of pita bread.
    3. If you continue the factory analogy, the addition of a molecular tag is like adding address labels in the shipping department of a factory.
  • Figure 4.18 Review of the endomembrane system
  • Figure 4.18a Review of the endomembrane system: art
  • Figure 4.18b Review of the endomembrane system: micrograph
  • <number>
    Student Misconceptions and Concerns
    1. Students often mistakenly think that chloroplasts are a substitute for mitochondria in plant cells. They may falsely think that cells either have mitochondria or they have chloroplasts. You might wish to emphasize the presence and significance of mitochondria and chloroplasts in plant cells.
    2. The evidence that mitochondria and chloroplasts evolved from free-living prokaryotes is further supported by the small prokaryote size of these organelles. Mitochondria and chloroplasts are therefore helpful in comparing the general size of eukaryotic and prokaryotic cells.
    Teaching Tips
    1. ATP functions in cells much like money functions in modern societies. Each holds value that can be generated in one place and spent in another. This analogy has been very helpful for many students.
    2. Mitochondria and chloroplasts are each wrapped by multiple membranes. In both organelles, the innermost membranes are the sites of greatest molecular activity and the outer membranes have fewer significant functions. These outer membranes best correspond to the plasma membrane of the eukaryotic cells that originally wrapped the free-living prokaryotes during endocytosis.
    3. Mitochondria and chloroplasts are not cellular structures that are synthesized in a cell like ribosomes and lysosomes. Instead, mitochondria only come from other mitochondria and chloroplasts only come from other chloroplasts. This is further evidence of the independent evolution of these organelles from free-living ancestral forms.
  • <number>
    Student Misconceptions and Concerns
    1. Students often mistakenly think that chloroplasts are a substitute for mitochondria in plant cells. They may falsely think that cells either have mitochondria or they have chloroplasts. You might wish to emphasize the presence and significance of mitochondria and chloroplasts in plant cells.
    2. The evidence that mitochondria and chloroplasts evolved from free-living prokaryotes is further supported by the small prokaryote size of these organelles. Mitochondria and chloroplasts are therefore helpful in comparing the general size of eukaryotic and prokaryotic cells.
    Teaching Tips
    1. ATP functions in cells much like money functions in modern societies. Each holds value that can be generated in one place and spent in another. This analogy has been very helpful for many students.
    2. Mitochondria and chloroplasts are each wrapped by multiple membranes. In both organelles, the innermost membranes are the sites of greatest molecular activity and the outer membranes have fewer significant functions. These outer membranes best correspond to the plasma membrane of the eukaryotic cells that originally wrapped the free-living prokaryotes during endocytosis.
    3. Mitochondria and chloroplasts are not cellular structures that are synthesized in a cell like ribosomes and lysosomes. Instead, mitochondria only come from other mitochondria and chloroplasts only come from other chloroplasts. This is further evidence of the independent evolution of these organelles from free-living ancestral forms.
  • <number>
    Student Misconceptions and Concerns
    1. Students often mistakenly think that chloroplasts are a substitute for mitochondria in plant cells. They may falsely think that cells either have mitochondria or they have chloroplasts. You might wish to emphasize the presence and significance of mitochondria and chloroplasts in plant cells.
    2. The evidence that mitochondria and chloroplasts evolved from free-living prokaryotes is further supported by the small prokaryote size of these organelles. Mitochondria and chloroplasts are therefore helpful in comparing the general size of eukaryotic and prokaryotic cells.
    Teaching Tips
    1. ATP functions in cells much like money functions in modern societies. Each holds value that can be generated in one place and spent in another. This analogy has been very helpful for many students.
    2. Mitochondria and chloroplasts are each wrapped by multiple membranes. In both organelles, the innermost membranes are the sites of greatest molecular activity and the outer membranes have fewer significant functions. These outer membranes best correspond to the plasma membrane of the eukaryotic cells that originally wrapped the free-living prokaryotes during endocytosis.
    3. Mitochondria and chloroplasts are not cellular structures that are synthesized in a cell like ribosomes and lysosomes. Instead, mitochondria only come from other mitochondria and chloroplasts only come from other chloroplasts. This is further evidence of the independent evolution of these organelles from free-living ancestral forms.
  • Figure 4.19 The chloroplast: site of photosynthesis
  • Figure 4.19a Chloroplast: art
  • Figure 4.19b Chloroplast: TEM
  • <number>
    Student Misconceptions and Concerns
    1. Students often mistakenly think that chloroplasts are a substitute for mitochondria in plant cells. They may falsely think that cells either have mitochondria or they have chloroplasts. You might wish to emphasize the presence and significance of mitochondria and chloroplasts in plant cells.
    2. The evidence that mitochondria and chloroplasts evolved from free-living prokaryotes is further supported by the small prokaryote size of these organelles. Mitochondria and chloroplasts are therefore helpful in comparing the general size of eukaryotic and prokaryotic cells.
    Teaching Tips
    1. ATP functions in cells much like money functions in modern societies. Each holds value that can be generated in one place and spent in another. This analogy has been very helpful for many students.
    2. Mitochondria and chloroplasts are each wrapped by multiple membranes. In both organelles, the innermost membranes are the sites of greatest molecular activity and the outer membranes have fewer significant functions. These outer membranes best correspond to the plasma membrane of the eukaryotic cells that originally wrapped the free-living prokaryotes during endocytosis.
    3. Mitochondria and chloroplasts are not cellular structures that are synthesized in a cell like ribosomes and lysosomes. Instead, mitochondria only come from other mitochondria and chloroplasts only come from other chloroplasts. This is further evidence of the independent evolution of these organelles from free-living ancestral forms.
  • <number>
    Student Misconceptions and Concerns
    1. Students often mistakenly think that chloroplasts are a substitute for mitochondria in plant cells. They may falsely think that cells either have mitochondria or they have chloroplasts. You might wish to emphasize the presence and significance of mitochondria and chloroplasts in plant cells.
    2. The evidence that mitochondria and chloroplasts evolved from free-living prokaryotes is further supported by the small prokaryote size of these organelles. Mitochondria and chloroplasts are therefore helpful in comparing the general size of eukaryotic and prokaryotic cells.
    Teaching Tips
    1. ATP functions in cells much like money functions in modern societies. Each holds value that can be generated in one place and spent in another. This analogy has been very helpful for many students.
    2. Mitochondria and chloroplasts are each wrapped by multiple membranes. In both organelles, the innermost membranes are the sites of greatest molecular activity and the outer membranes have fewer significant functions. These outer membranes best correspond to the plasma membrane of the eukaryotic cells that originally wrapped the free-living prokaryotes during endocytosis.
    3. Mitochondria and chloroplasts are not cellular structures that are synthesized in a cell like ribosomes and lysosomes. Instead, mitochondria only come from other mitochondria and chloroplasts only come from other chloroplasts. This is further evidence of the independent evolution of these organelles from free-living ancestral forms.
  • Figure 4.20 The mitochondrion: site of cellular respiration
  • Figure 4.20a Mitochondrion: art
  • Figure 4.20b Mitochondrion: TEM
  • <number>
    Student Misconceptions and Concerns
    1. Students often mistakenly think that chloroplasts are a substitute for mitochondria in plant cells. They may falsely think that cells either have mitochondria or they have chloroplasts. You might wish to emphasize the presence and significance of mitochondria and chloroplasts in plant cells.
    2. The evidence that mitochondria and chloroplasts evolved from free-living prokaryotes is further supported by the small prokaryote size of these organelles. Mitochondria and chloroplasts are therefore helpful in comparing the general size of eukaryotic and prokaryotic cells.
    Teaching Tips
    1. ATP functions in cells much like money functions in modern societies. Each holds value that can be generated in one place and spent in another. This analogy has been very helpful for many students.
    2. Mitochondria and chloroplasts are each wrapped by multiple membranes. In both organelles, the innermost membranes are the sites of greatest molecular activity and the outer membranes have fewer significant functions. These outer membranes best correspond to the plasma membrane of the eukaryotic cells that originally wrapped the free-living prokaryotes during endocytosis.
    3. Mitochondria and chloroplasts are not cellular structures that are synthesized in a cell like ribosomes and lysosomes. Instead, mitochondria only come from other mitochondria and chloroplasts only come from other chloroplasts. This is further evidence of the independent evolution of these organelles from free-living ancestral forms.
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • Figure 4.21 The cytoskeleton
  • Figure 4.21a Microtubules in the cytoskeleton
  • Figure 4.21b Microtubules and movement
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • Figure 4.22 Flagella and cilia
  • Figure 4.22a Flagellum of a human sperm cell
  • Figure 4.22b Cilia on a protist
  • Figure 4.22c Cilia lining the respiratory tract
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • <number>
    Student Misconceptions and Concerns
    1. Students often regard the fluid of the cytoplasm as little more than a watery fluid, which suspends the organelles. The diverse functions of thin, thick, and intermediate filaments are rarely appreciated before college.
    2. Students often think that the cilia on the cells lining our trachea function like a comb, removing debris from the air. Except in cases of disease or damage, these respiratory cilia are instead covered by mucus. Cilia lining our trachea do not reach the air to comb it. Instead, these cilia sweep the dirty mucus up our respiratory tracts. (See also Teaching Tip #2 below.)
    3. The dynamic, web-like structure of the cytoskeleton is very different from the skeletons that students may already know. Their dynamic structures (see Teaching Tip #2 below) are quite unlike any human designs. Students have much to gain from vivid illustrations of cytoskeletal diversity. Consider sharing some impressive images from a Google image search or other resources.
    Teaching Tips
    1. Students might enjoy this brief class activity. Have everyone in the class clear their throats at the same time. Wait a few seconds. Have them notice that after clearing, they swallowed. The mucus that trapped debris is swept up the trachea by cilia. When we clear our throats, this dirty mucus is disposed of down our esophagus and amongst the strong acids of our stomach!
    2. Analogies between the infrastructure of human buildings and the cytoskeleton are limited by the dynamic nature of the cytoskeleton. Few human structures have their structural framework routinely constructed, deconstructed, and then reformed in a new configuration on a regular basis. (Tents are often constructed, deconstructed, and then reformed repeatedly but typically rely upon the same basic design.) Thus, caution is especially warranted in such analogies.
  • Figure 4.23 The changing role of antibiotics
  • Figure 4.23a Penicillin poster
  • Figure 4.23b CDC poster
  • Figure UN1 Plasma membrane orientation figure
  • Figure UN2 Nucleus orientation
  • Figure UN3 Ribosome orientation
  • Figure UN4 Endoplasmic reticulum orientation
  • Figure UN5 Golgi apparatus orientation
  • Figure UN6 Lysosome orientation
  • Figure UN7 Vacuole orientation
  • Figure UN8 Chloroplast orientation
  • Figure UN9 Mitochondrion orientation
  • Figure UN10 Cytoskeleton orientation
  • Figure UN11 Cilia and flagella orientation
  • Figure UN12 Summary: categories of cells
  • Figure UN13 Summary: plasma membrane
  • Figure UN14 Summary: chloroplast and mitochondrion
  • Transcript

    • 1. © 2010 Pearson Education, Inc. Lectures by Chris C. Romero, updated by Edward J. Zalisko PowerPoint® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Chapter 4 A Tour of the Cell
    • 2. Biology and Society: Drugs That Target Bacterial Cells • Antibiotics were first isolated from mold in 1928. • The widespread use of antibiotics drastically decreased deaths from bacterial infections. © 2010 Pearson Education, Inc.
    • 3. ColorizedTEM Figure 4.00
    • 4. © 2010 Pearson Education, Inc. • Most antibiotics kill bacteria while minimally harming the human host by binding to structures found only on bacterial cells. • Some antibiotics bind to the bacterial ribosome, leaving human ribosomes unaffected. • Other antibiotics target enzymes found only in the bacterial cells.
    • 5. © 2010 Pearson Education, Inc. THE MICROSCOPIC WORLD OF CELLS • Organisms are either – Single-celled, such as most prokaryotes and protists or – Multicelled, such as plants, animals, and most fungi
    • 6. © 2010 Pearson Education, Inc. Microscopes as Windows on the World of Cells • Light microscopes can be used to explore the structures and functions of cells. • When scientists examine a specimen on a microscope slide – Light passes through the specimen – Lenses enlarge, or magnify, the image
    • 7. Light Micrograph (LM) (for viewing living cells) Light micrograph of a protist, Paramecium LM ColorizedSEM Scanning Electron Micrograph (SEM) (for viewing surface features) Scanning electron micrograph of Paramecium TYPES OF MICROGRAPHS Transmission Electron Micrograph (TEM) (for viewing internal structures) Transmission electron micrograph of Paramecium ColorizedTEM Figure 4.1
    • 8. Light Micrograph (LM) (for viewing living cells) Light micrograph of a protist, Paramecium LM Figure 4.1a
    • 9. ColorizedSEM Scanning Electron Micrograph (SEM) (for viewing surface features) Scanning electron micrograph of Paramecium Figure 4.1b
    • 10. Transmission Electron Micrograph (TEM) (for viewing internal structures) Transmission electron micrograph of Paramecium ColorizedTEM Figure 4.1c
    • 11. © 2010 Pearson Education, Inc. • Magnification is an increase in the specimen’s apparent size. • Resolving power is the ability of an optical instrument to show two objects as separate.
    • 12. © 2010 Pearson Education, Inc. • Cells were first described in 1665 by Robert Hooke. • The accumulation of scientific evidence led to the cell theory. – All living things are composed of cells. – All cells come from other cells.
    • 13. © 2010 Pearson Education, Inc. • The electron microscope (EM) uses a beam of electrons, which results in better resolving power than the light microscope. • Two kinds of electron microscopes reveal different parts of cells.
    • 14. © 2010 Pearson Education, Inc. • Scanning electron microscopes examine cell surfaces.
    • 15. © 2010 Pearson Education, Inc. • Transmission electron microscopes (TEM) are useful for internal details of cells.
    • 16. © 2010 Pearson Education, Inc. • The electron microscope can – Magnify up to 100,000 times – Distinguish between objects 0.2 nanometers apart
    • 17. Figure 4.2
    • 18. 10 m 1 m 10 cm 1 cm 1 mm 100 mm 10 mm Human height Chicken egg Frog eggs Length of some nerve and muscle cells Unaidedeye Lightmicroscope Plant and animal cells Most bacteria Nucleus Mitochondrion 1 mm 100 nm 10 nm 1 nm 0.1 nm Smallest bacteria Viruses Ribosomes Proteins Lipids Small molecules Atoms Electronmicroscope Figure 4.3
    • 19. © 2010 Pearson Education, Inc. The Two Major Categories of Cells • The countless cells on earth fall into two categories: – Prokaryotic cells — Bacteria and Archaea – Eukaryotic cells — plants, fungi, and animals • All cells have several basic features. – They are all bound by a thin plasma membrane. – All cells have DNA and ribosomes, tiny structures that build proteins.
    • 20. © 2010 Pearson Education, Inc. • Prokaryotic and eukaryotic cells have important differences. • Prokaryotic cells are older than eukaryotic cells. – Prokaryotes appeared about 3.5 billion years ago. – Eukaryotes appeared about 2.1 billion years ago.
    • 21. © 2010 Pearson Education, Inc. • Prokaryotes – Are smaller than eukaryotic cells – Lack internal structures surrounded by membranes – Lack a nucleus – Have a rigid cell wall
    • 22. © 2010 Pearson Education, Inc. • Eukaryotes – Only eukaryotic cells have organelles, membrane-bound structures that perform specific functions. – The most important organelle is the nucleus, which houses most of a eukaryotic cell’s DNA.
    • 23. Plasma membrane (encloses cytoplasm) Cell wall (provides Rigidity) Capsule (sticky coating) Prokaryotic flagellum (for propulsion) Ribosomes (synthesize proteins) Nucleoid (contains DNA) Pili (attachment structures) ColorizedTEM Figure 4.4
    • 24. Plasma membrane (encloses cytoplasm) Cell wall (provides rigidity) Capsule (sticky coating) Prokaryotic flagellum (for propulsion) Ribosomes (synthesize proteins) Nucleoid (contains DNA) Pili (attachment structures) Figure 4.4a
    • 25. ColorizedTEM Figure 4.4b
    • 26. © 2010 Pearson Education, Inc. An Overview of Eukaryotic Cells • Eukaryotic cells are fundamentally similar. • The region between the nucleus and plasma membrane is the cytoplasm. • The cytoplasm consists of various organelles suspended in fluid.
    • 27. © 2010 Pearson Education, Inc. • Unlike animal cells, plant cells have – Protective cell walls – Chloroplasts, which convert light energy to the chemical energy of food Blast Animation: Plant Cell Overview Blast Animation: Animal Cell Overview
    • 28. Cytoskeleton Ribosomes Centriole Lysosome Flagellum Nucleus Plasma membrane Mitochondrion Rough endoplasmic reticulum (ER) Golgi apparatus Smooth endoplasmic reticulum (ER) Idealized animal cell Idealized plant cell Cytoskeleton Mitochondrion Nucleus Rough endoplasmic reticulum (ER) Ribosomes Smooth endoplasmic reticulum (ER) Golgi apparatus Plasma membrane Channels between cells Not in most plant cells Central vacuole Cell wall Chloroplast Not in animal cells Figure 4.5
    • 29. Cytoskeleton Ribosomes Centriole Lysosome Flagellum Nucleus Plasma membrane Mitochondrion Rough endoplasmic reticulum (ER) Golgi apparatus Smooth endoplasmic reticulum (ER) Idealized animal cell Not in most plant cells Figure 4.5a
    • 30. Idealized plant cell Cytoskeleton Mitochondrion Nucleus Rough endoplasmic reticulum (ER) Ribosomes Smooth endoplasmic reticulum (ER) Golgi apparatus Plasma membrane Channels between cells Central vacuole Cell wall Chloroplast Not in animal cells Figure 4.5b
    • 31. © 2010 Pearson Education, Inc. MEMBRANE STRUCTURE • The plasma membrane separates the living cell from its nonliving surroundings.
    • 32. The Plasma Membrane: A Fluid Mosaic of Lipids and Proteins • The membranes of cells are composed mostly of – Lipids – Proteins © 2010 Pearson Education, Inc.
    • 33. © 2010 Pearson Education, Inc. • The lipids belong to a special category called phospholipids. • Phospholipids form a two-layered membrane, the phospholipid bilayer. Animation: Tight Junctions Animation: Gap Junctions Animation: Desmosomes
    • 34. (a) Phospholipid bilayer of membrane (b) Fluid mosaic model of membrane Outside of cell Outside of cell Hydrophilic head Hydrophobic tail Hydrophilic region of protein Hydrophilic head Hydrophobic tail Hydrophobic regions of protein Phospholipid bilayer Phospholipid Proteins Cytoplasm (inside of cell) Cytoplasm (inside of cell) Figure 4.6
    • 35. (a) Phospholipid bilayer of membrane Outside of cell Hydrophilic head Hydrophobic tail Phospholipid Cytoplasm (inside of cell) Figure 4.6a
    • 36. (b) Fluid mosaic model of membrane Outside of cell Hydrophilic region of protein Hydrophilic head Hydrophobic tail Hydrophobic regions of protein Phospholipid bilayer Proteins Cytoplasm (inside of cell) Figure 4.6b
    • 37. © 2010 Pearson Education, Inc. • Most membranes have specific proteins embedded in the phospholipid bilayer. • These proteins help regulate traffic across the membrane and perform other functions.
    • 38. © 2010 Pearson Education, Inc. • The plasma membrane is a fluid mosaic: – Fluid because molecules can move freely past one another – A mosaic because of the diversity of proteins in the membrane
    • 39. © 2010 Pearson Education, Inc. The Process of Science: What Makes a Superbug? • Observation: Bacteria use a protein called PSM to disable human immune cells by forming holes in the plasma membrane. • Question: Does PSM play a role in MRSA infections? • Hypothesis: MRSA bacteria lacking the ability to produce PSM would be less deadly than normal MRSA strains.
    • 40. © 2010 Pearson Education, Inc. • Experiment: Researchers infected – Seven mice with normal MRSA – Eight mice with MRSA that does not produce PSM • Results: – All seven mice infected with normal MRSA died. – Five of the eight mice infected with MRSA that does not produce PSM survived.
    • 41. © 2010 Pearson Education, Inc. • Conclusions: – MRSA strains appear to use the membrane-destroying PSM protein, but – Factors other than PSM protein contributed to the death of mice
    • 42. MRSA bacterium producing PSM proteins Methicillin-resistant Staphylococcus aureus (MRSA) ColorizedSEM Figure 4.7-1
    • 43. MRSA bacterium producing PSM proteins Methicillin-resistant Staphylococcus aureus (MRSA) ColorizedSEM PSM proteins forming hole in human immune cell plasma membrane Plasma membrane PSM protein Pore Figure 4.7-2
    • 44. MRSA bacterium producing PSM proteins Methicillin-resistant Staphylococcus aureus (MRSA) ColorizedSEM PSM proteins forming hole in human immune cell plasma membrane Plasma membrane PSM protein Pore Cell bursting, losing its contents through the pores Figure 4.7-3
    • 45. © 2010 Pearson Education, Inc. Cell Surfaces • Plant cells have rigid cell walls surrounding the membrane. • Plant cell walls – Are made of cellulose – Protect the cells – Maintain cell shape – Keep the cells from absorbing too much water
    • 46. © 2010 Pearson Education, Inc. • Animal cells – Lack cell walls – Have an extracellular matrix, which – Helps hold cells together in tissues – Protects and supports them • The surfaces of most animal cells contain cell junctions, structures that connect to other cells.
    • 47. THE NUCLEUS AND RIBOSOMES: GENETIC CONTROL OF THE CELL • The nucleus is the chief executive of the cell. – Genes in the nucleus store information necessary to produce proteins. – Proteins do most of the work of the cell. © 2010 Pearson Education, Inc.
    • 48. © 2010 Pearson Education, Inc. Structure and Function of the Nucleus • The nucleus is bordered by a double membrane called the nuclear envelope. • Pores in the envelope allow materials to move between the nucleus and cytoplasm. • The nucleus contains a nucleolus where ribosomes are made.
    • 49. Ribosomes Chromatin Nucleolus Pore Nuclear envelope Surface of nuclear envelope Nuclear pores TEM TEM Figure 4.8
    • 50. Ribosomes Chromatin Nucleolus Pore Nuclear envelope Figure 4.8a
    • 51. Surface of nuclear envelope TEM Figure 4.8b
    • 52. Nuclear pores TEM Figure 4.8c
    • 53. © 2010 Pearson Education, Inc. • Stored in the nucleus are long DNA molecules and associated proteins that form fibers called chromatin. • Each long chromatin fiber constitutes one chromosome. • The number of chromosomes in a cell depends on the species.
    • 54. DNA molecule Chromosome Proteins Chromatin fiber Figure 4.9
    • 55. © 2010 Pearson Education, Inc. Ribosomes • Ribosomes are responsible for protein synthesis. • Ribosome components are made in the nucleolus but assembled in the cytoplasm.
    • 56. Ribosome Protein mRNA Figure 4.10
    • 57. © 2010 Pearson Education, Inc. • Ribosomes may assemble proteins: – Suspended in the fluid of the cytoplasm or – Attached to the outside of an organelle called the endoplasmic reticulum
    • 58. Ribosomes in cytoplasm Ribosomes attached to endoplasmic reticulum TEM Figure 4.11
    • 59. © 2010 Pearson Education, Inc. How DNA Directs Protein Production • DNA directs protein production by transferring its coded information into messenger RNA (mRNA). • Messenger RNA exits the nucleus through pores in the nuclear envelope. • A ribosome moves along the mRNA translating the genetic message into a protein with a specific amino acid sequence.
    • 60. Synthesis of mRNA in the nucleus Nucleus DNA mRNA Cytoplasm Figure 4.12-1
    • 61. Synthesis of mRNA in the nucleus Nucleus DNA mRNA Cytoplasm mRNAMovement of mRNA into cytoplasm via nuclear pore Figure 4.12-2
    • 62. Synthesis of mRNA in the nucleus Nucleus DNA mRNA Cytoplasm mRNAMovement of mRNA into cytoplasm via nuclear pore Ribosome Protein Synthesis of protein in the cytoplasm Figure 4.12-3
    • 63. THE ENDOMEMBRANE SYSTEM: MANUFACTURING AND DISTRIBUTING CELLULAR PRODUCTS • Many membranous organelles forming the endomembrane system in a cell are interconnected either – Directly or – Through the transfer of membrane segments between them © 2010 Pearson Education, Inc.
    • 64. © 2010 Pearson Education, Inc. The Endoplasmic Reticulum • The endoplasmic reticulum (ER) is one of the main manufacturing facilities in a cell. • The ER – Produces an enormous variety of molecules – Is composed of smooth and rough ER
    • 65. Nuclear envelope Smooth ERRough ER Ribosomes Ribosomes TEM Figure 4.13
    • 66. Nuclear envelope Smooth ERRough ER Ribosomes Figure 4.13a
    • 67. Ribosomes TEM Rough ER Smooth ER Figure 4.13b
    • 68. © 2010 Pearson Education, Inc. Rough ER • The “rough” in the rough ER is due to ribosomes that stud the outside of the ER membrane. • These ribosomes produce membrane proteins and secretory proteins. • After the rough ER synthesizes a molecule, it packages the molecule into transport vesicles.
    • 69. Proteins are often modified in the ER. Secretory proteins depart in transport vesicles. Vesicles bud off from the ER. A ribosome links amino acids into a polypeptide. Ribosome Transport vesicle Polypeptide Protein Rough ER Figure 4.14
    • 70. © 2010 Pearson Education, Inc. Smooth ER • The smooth ER – Lacks surface ribosomes – Produces lipids, including steroids – Helps liver cells detoxify circulating drugs
    • 71. © 2010 Pearson Education, Inc. The Golgi Apparatus • The Golgi apparatus – Works in partnership with the ER – Receives, refines, stores, and distributes chemical products of the cell Video: Euglena
    • 72. “Receiving” side of Golgi apparatus New vesicle forming Transport vesicle from rough ER “Receiving” side of Golgi apparatus New vesicle forming Transport vesicle from the Golgi Plasma membrane “Shipping” side of Golgi apparatus ColorizedSEM Figure 4.15
    • 73. Transport vesicle from rough ER “Receiving” side of Golgi apparatus New vesicle forming Transport vesicle from the Golgi Plasma membrane “Shipping” side of Golgi apparatus Figure 4.15a
    • 74. “Receiving” side of Golgi apparatus New vesicle forming ColorizedSEM Figure 4.15b
    • 75. © 2010 Pearson Education, Inc. Lysosomes • A lysosome is a sac of digestive enzymes found in animal cells. • Enzymes in a lysosome can break down large molecules such as – Proteins – Polysaccharides – Fats – Nucleic acids
    • 76. © 2010 Pearson Education, Inc. • Lysosomes have several types of digestive functions. – Many cells engulf nutrients in tiny cytoplasmic sacs called food vacuoles. – These food vacuoles fuse with lysosomes, exposing food to enzymes to digest the food. – Small molecules from digestion leave the lysosome and nourish the cell. Animation: Lysosome Formation
    • 77. Plasma membrane Digestive enzymes Lysosome Digestion Food vacuole Lysosome Digestion (a) Lysosome digesting food (b) Lysosome breaking down the molecules of damaged organelles Vesicle containing damaged organelle Vesicle containing two damaged organelles Organelle fragment Organelle fragment TEM Figure 4.16
    • 78. Plasma membrane Digestive enzymes Lysosome Digestion Food vacuole (a) Lysosome digesting food Figure 4.16a
    • 79. Lysosome Digestion (b) Lysosome breaking down the molecules of damaged organelles Vesicle containing damaged organelle Figure 4.16b
    • 80. Vesicle containing two damaged organelles Organelle fragment Organelle fragment TEM Figure 4.16c
    • 81. © 2010 Pearson Education, Inc. • Lysosomes can also – Destroy harmful bacteria – Break down damaged organelles
    • 82. © 2010 Pearson Education, Inc. Vacuoles • Vacuoles are membranous sacs that bud from the – ER – Golgi – Plasma membrane
    • 83. © 2010 Pearson Education, Inc. • Contractile vacuoles of protists pump out excess water in the cell. • Central vacuoles of plants – Store nutrients – Absorb water – May contain pigments or poisons Video: Cytoplasmic Streaming Blast Animation: Vacuole Video: Paramecium Vacuole
    • 84. Vacuole filling with water Vacuole contracting (a) Contractile vacuole in Paramecium (b) Central vacuole in a plant cell Central vacuole ColorizedTEM LMLM Figure 4.17
    • 85. Figure 4.17a Vacuole filling with water Vacuole contracting (a) Contractile vacuole in Paramecium TEMTEM
    • 86. (b) Central vacuole in a plant cell Central vacuole ColorizedTEM Figure 4.17b
    • 87. © 2010 Pearson Education, Inc. • To review, the endomembrane system interconnects the – Nuclear envelope – ER – Golgi – Lysosomes – Vacuoles – Plasma membrane Blast Animation : Vesicle Transport Along Microtubules Video: Chlamydomonas
    • 88. Golgi apparatus Transport vesicle Plasma membrane Secretory protein New vesicle forming Transport vesicle from the Golgi Vacuoles store some cell products. Lysosomes carrying digestive enzymes can fuse with other vesicles. Transport vesicles carry enzymes and other proteins from the rough ER to the Golgi for processing. Some products are secreted from the cell. Golgi apparatus Rough ER Vacuole Lysosome Transport vesicle TEM Figure 4.18
    • 89. Golgi apparatus Transport vesicle Plasma membrane Secretory protein Vacuoles store some cell products. Lysosomes carrying digestive enzymes can fuse with other vesicles. Transport vesicles carry enzymes and other proteins from the rough ER to the Golgi for processing. Some products are secreted from the cell. Rough ER Vacuole Lysosome Transport vesicle Figure 4.18a
    • 90. New vesicle forming Transport vesicle from the Golgi Golgi apparatus TEM Figure 4.18b
    • 91. CHLOROPLASTS AND MITOCHONDRIA: ENERGY CONVERSION • Cells require a constant energy supply to perform the work of life. © 2010 Pearson Education, Inc.
    • 92. © 2010 Pearson Education, Inc. Chloroplasts • Most of the living world runs on the energy provided by photosynthesis. • Photosynthesis is the conversion of light energy from the sun to the chemical energy of sugar. • Chloroplasts are the organelles that perform photosynthesis.
    • 93. © 2010 Pearson Education, Inc. • Chloroplasts have three major compartments: – The space between the two membranes – The stroma, a thick fluid within the chloroplast – The space within grana, the structures that trap light energy and convert it to chemical energy
    • 94. Inner and outer membranes Space between membranes Stroma (fluid in chloroplast) Granum TEM Figure 4.19
    • 95. Inner and outer membranes Space between membranes Stroma (fluid in chloroplast) Granum Figure 4.19a
    • 96. Stroma (fluid in chloroplast) Granum TEM Figure 4.19b
    • 97. © 2010 Pearson Education, Inc. Mitochondria • Mitochondria are the sites of cellular respiration, which produce ATP from the energy of food molecules. • Mitochondria are found in almost all eukaryotic cells.
    • 98. © 2010 Pearson Education, Inc. • An envelope of two membranes encloses the mitochondrion. These consist of – An outer smooth membrane – An inner membrane that has numerous infoldings called cristae Blast Animation: Mitochondrion
    • 99. Outer membrane Inner membrane Cristae Matrix Space between membranes TEM Figure 4.20
    • 100. Outer membrane Inner membrane Cristae Matrix Space between membranes Figure 4.20a
    • 101. Outer membrane Inner membrane Cristae Matrix Space between membranes TEM Figure 4.20b
    • 102. © 2010 Pearson Education, Inc. • Mitochondria and chloroplasts contain their own DNA, which encodes some of their proteins. • This DNA is evidence that mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past.
    • 103. THE CYTOSKELETON: CELL SHAPE AND MOVEMENT • The cytoskeleton is a network of fibers extending throughout the cytoplasm. © 2010 Pearson Education, Inc.
    • 104. © 2010 Pearson Education, Inc. Maintaining Cell Shape • The cytoskeleton – Provides mechanical support to the cell – Maintains its shape
    • 105. © 2010 Pearson Education, Inc. • The cytoskeleton contains several types of fibers made from different proteins: – Microtubules – Are straight and hollow – Guide the movement of organelles and chromosomes – Intermediate filaments and microfilaments are thinner and solid.
    • 106. (a) Microtubules in the cytoskeleton (b) Microtubules and movement LM LM Figure 4.21
    • 107. (a) Microtubules in the cytoskeleton LM Figure 4.21a
    • 108. (b) Microtubules and movement LM Figure 4.21b
    • 109. © 2010 Pearson Education, Inc. • The cytoskeleton is dynamic. • Changes in the cytoskeleton contribute to the amoeboid motion of an Amoeba.
    • 110. © 2010 Pearson Education, Inc. Cilia and Flagella • Cilia and flagella aid in movement. – Flagella propel the cell in a whiplike motion. – Cilia move in a coordinated back-and-forth motion. – Cilia and flagella have the same basic architecture. Animation: Cilia and Flagella Video: Paramecium Cilia Video: Prokaryotic Flagella (Salmonella typhimurium) Video: Euglena
    • 111. (a) Flagellum of a human sperm cell ColorizedSEM (b) Cilia on a protist (c) Cilia lining the respiratory tract ColorizedSEM ColorizedSEM Figure 4.22
    • 112. (a) Flagellum of a human sperm cell ColorizedSEM Figure 4.22a
    • 113. (b) Cilia on a protist ColorizedSEM Figure 4.22b
    • 114. ColorizedSEM (c) Cilia lining the respiratory tract Figure 4.22c
    • 115. © 2010 Pearson Education, Inc. • Cilia may extend from nonmoving cells. • On cells lining the human trachea, cilia help sweep mucus out of the lungs.
    • 116. Evolution Connection: The Evolution of Antibiotic Resistance • Many antibiotics disrupt cellular structures of invading microorganisms. • Introduced in the 1940s, penicillin worked well against such infections. • But over time, bacteria that were resistant to antibiotics were favored. • The widespread use and abuse of antibiotics continues to favor bacteria that resist antibiotics. © 2010 Pearson Education, Inc.
    • 117. Figure 4.23
    • 118. Figure 4.23a
    • 119. Figure 4.23b
    • 120. Figure 4.UN1
    • 121. Figure 4.UN2
    • 122. Figure 4.UN3
    • 123. Figure 4.UN4
    • 124. Figure 4.UN5
    • 125. Figure 4.UN6
    • 126. Figure 4.UN7
    • 127. Figure 4.UN8
    • 128. Figure 4.UN9
    • 129. Figure 4.UN10
    • 130. Figure 4.UN11
    • 131. Prokaryotic Cells Eukaryotic Cells • Smaller • Simpler • Most do not have organelles • Found in bacteria and archaea • Larger • More complex • Have organelles • Found in protists, plants, fungi, animals CATEGORIES OF CELLS Figure 4.UN12
    • 132. Outside of cell Cytoplasm (inside of cell) Protein Phospholipid Hydrophilic Hydrophilic Hydrophobic Figure 4.UN13
    • 133. Light energy Chloroplast Mitochondrion Chemical energy (food) ATPPHOTOSYNTHESIS CELLULAR RESPIRATION Figure 4.UN14