Chapter Seven- The Cell

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Chapter seven lecture for Lab Biology on the cell.

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Chapter Seven- The Cell

  1. 1. 7-1 Life Is Cellular Copyright Pearson Prentice Hall
  2. 2. The Discovery of the Cell Cells are the basic units of life. Copyright Pearson Prentice Hall
  3. 3. The Discovery of the Cell The cell theory states: •All living things are composed of cells. •Cells are the basic units of structure and function in living things. •New cells are produced from existing cells. Copyright Pearson Prentice Hall
  4. 4. Exploring the Cell Electron Microscopes •1000 times more powerful than light microscopes. •used to visualize nonliving, preserved cells and tissues. Transmission electron microscopes (TEMs) Used to study cell structures and large protein molecules Specimens must be cut into ultra-thin slices Scanning electron microscopes (SEMs) Produce three-dimensional images of cells Specimens do not have to be cut into thin slices Copyright Pearson Prentice Hall
  5. 5. Exploring the Cell Scanning Electron Micrograph of Neurons Copyright Pearson Prentice Hall
  6. 6. Exploring the Cell Confocal Light Microscopes Confocal light microscopes scan cells with a laser beam. This makes it possible to build three-dimensional images of Copyright Pearson Prentice Hall cells and their parts.
  7. 7. Exploring the Cell Scanning Probe Microscopes Scanning probe microscopes allow us to observe single atoms. Images are produced by tracing surfaces of samples with a fine probe. Copyright Pearson Prentice Hall DNA
  8. 8. Prokaryotes and Eukaryotes Cells come in a variety of shapes and sizes. All cells: • are surrounded by a barrier called a cell membrane. • at some point contain DNA. Copyright Pearson Prentice Hall
  9. 9. Cells are classified into two categories, depending on whether they contain a nucleus. The nucleus is a membrane-enclosed structure that contains the cell's genetic material in the form of DNA. The nucleus controls many of the cell's activities. Copyright Pearson Prentice Hall
  10. 10. Eukaryotes- cells contain nuclei. ~ ~ nucleus ~ ~ Prokaryotes- cells do not contain nuclei. ~ ~ DNA just floats ~ around ~ ~ Copyright Pearson Prentice Hall
  11. 11. Prokaryotic cells are simpler than eukaryotic cells. Bacteria are prokaryotes. Copyright Pearson Prentice Hall
  12. 12. Eukaryotic cells are generally larger and more complex than prokaryotic cells. Eukaryotic cells generally contain dozens of structures and internal membranes. Many eukaryotic cells are highly specialized. Plants, animals, fungi, and protists are eukaryotes. Copyright Pearson Prentice Hall
  13. 13. 7-2 Eukaryotic Cell Structure Copyright Pearson Prentice Hall
  14. 14. The parts that make up a eukaryotic cell are known as organelles. Cell biologists divide the eukaryotic cell into two major sections: the nucleus and the cytoplasm. The Cytoplasm is the fluid outside the nucleus. Copyright Pearson Prentice Hall
  15. 15. ACTIVE ART go to PHSchool.com and type in web code cbp-3072 Copyright Pearson Prentice Hall Plant Cell Nuclear envelope Ribosome (free) Ribosome (attached) Golgi apparatus Mitochondrion Vacuole Nucleolus Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Cell wall Cell membrane Chloroplast
  16. 16. Eukaryotic Cell Structures Copyright Pearson Prentice Hall Smooth endoplasmic reticulum Ribosome (free) Ribosome (attached) Golgi apparatus Animal Cell Rough endoplasmic reticulum Mitochondrion Cell membrane Nucleus Nuclear envelope Nucleolus Centrioles
  17. 17. Draw two eukaryotic cells PLANT CELL ANIMAL CELL Nucleus Cytoplasm Cell membrane Draw and label- cell membrane, nucleus, cytoplasm. Copyright Pearson Prentice Hall
  18. 18. Nucleus Nucleus The nucleus is the control center of the cell. The nucleus contains nearly all the cell's DNA. DNA contains coded instructions for making proteins and other molecules. Copyright Pearson Prentice Hall
  19. 19. Nucleus Copyright Pearson Prentice Hall The Nucleus Nucleolus Nuclear envelope Nuclear pores Chromatin
  20. 20. Nucleus The nucleus is surrounded by a nuclear envelope composed of two membranes. The envelope is dotted with nuclear pores, which allow material to move in and out of the nucleus. Nuclear envelope Copyright Pearson Prentice Hall Nuclear pores
  21. 21. Nucleus The granular material in the nucleus is called chromatin (contains DNA and proteins). Copyright Pearson Prentice Hall
  22. 22. Nucleus When a cell divides, chromatin condenses to form chromosomes. Chromosomes contain the genetic information that is passed from one generation of cells to the next. Copyright Pearson Prentice Hall
  23. 23. Nucleus Most nuclei also contain a nucleolus. The nucleolus is where the assembly of ribosomes begins. Copyright Pearson Prentice Hall Nucleolus
  24. 24. Draw two eukaryotic cells PLANT CELL ANIMAL CELL Chromatin (DNA) Draw and label- chromatin(DNA) Copyright Pearson Prentice Hall
  25. 25. Ribosomes Ribosomes One of the most important jobs carried out in the cell is making proteins. Proteins are assembled on ribosomes found throughout the cytoplasm. Copyright Pearson Prentice Hall
  26. 26. Ribosomes Ribosomes produce proteins by following coded instructions that come from the nucleus. Cells that are active in protein synthesis are often packed with ribosomes. Copyright Pearson Prentice Hall Ribosome (free) Ribosome (attached)
  27. 27. Endoplasmic Reticulum Eukaryotic cells contain an internal membrane system called the endoplasmic reticulum, or ER. The endoplasmic reticulum is where lipids that make the cell membrane are assembled, along with proteins and other materials that are exported from the cell. Copyright Pearson Prentice Hall
  28. 28. Copyright Pearson Prentice Hall Endoplasmic Reticulum Ribosomes Endoplasmic Reticulum Ribosomes are found on the surface of rough ER.
  29. 29. Endoplasmic Reticulum There are two types of ER—rough and smooth. The portion of the ER involved in protein synthesis is called rough endoplasmic reticulum, or rough ER. Rough ER is abundant in cells that produce large amounts of protein for export. Copyright Pearson Prentice Hall
  30. 30. Endoplasmic Reticulum Smooth ER does not have ribosomes on its surface. Smooth ER contains collections of enzymes that perform specialized tasks, such as synthesis of membrane lipids and detoxification of drugs. Copyright Pearson Prentice Hall
  31. 31. Draw two eukaryotic cells PLANT CELL ANIMAL CELL ribosomes Endoplasmic reticulum Draw and label- ribosomes, endoplasmic reticulum Copyright Pearson Prentice Hall
  32. 32. Golgi Apparatus Proteins produced in the rough ER move into the Golgi apparatus. The Golgi apparatus appears as a stack of membranes. Copyright Pearson Prentice Hall
  33. 33. Golgi Apparatus The Golgi apparatus modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell. From the Golgi apparatus, proteins are then “shipped” to their final destinations throughout the cell or outside of the cell. Copyright Pearson Prentice Hall
  34. 34. Draw two eukaryotic cells PLANT CELL ANIMAL CELL Golgi apparatus Draw and label- golgi apparatus Copyright Pearson Prentice Hall
  35. 35. Lysosomes Lysosomes are filled with enzymes that can break down large molecules and old organelles. Lysosomes are like recycling centers! Copyright Pearson Prentice Hall
  36. 36. Vacuoles Vacuoles Some cells contain saclike structures called vacuoles that store materials such as water, salts, proteins, and carbohydrates. Copyright Pearson Prentice Hall
  37. 37. Vacuoles In many plant cells there is a single, large central vacuole filled with liquid. The pressure of the central vacuole allows plants to support heavy structures such as leaves and flowers. Vacuole Copyright Pearson Prentice Hall
  38. 38. Vacuoles Vacuoles are also found in some unicellular organisms and in some animals. The paramecium contains a contractile vacuole that pumps excess water out of the cell. Copyright Pearson Prentice Hall Contractile vacuole
  39. 39. Draw two eukaryotic cells PLANT CELL ANIMAL CELL Vacuole Draw and label- vacuole Copyright Pearson Prentice Hall
  40. 40. Mitochondria and Chloroplasts Copyright Pearson Prentice Hall Mitochondrion = power Nearly all eukaryotic cells contain mitochondria. Mitochondria convert food molecules into a more usable energy source.
  41. 41. Mitochondria and Chloroplasts Mitochondria are enclosed by two membranes— an outer membrane and an inner membrane. The inner membrane is folded up inside the organelle. Copyright Pearson Prentice Hall
  42. 42. Mitochondria and Chloroplasts Chloroplast Chloroplasts Plants and some other organisms contain GREEN chloroplasts. Chloroplasts capture energy from sunlight and convert it into chemical energy during photosynthesis.
  43. 43. Mitochondria and Chloroplasts Chloroplasts are surrounded by two membranes. Chloroplasts contain the green pigment chlorophyll. Copyright Pearson Prentice Hall
  44. 44. Draw two eukaryotic cells PLANT CELL ANIMAL CELL Mitochondria Draw and label- mitochondria, chloroplasts Copyright Pearson Prentice Hall Chloroplasts
  45. 45. Cytoskeleton Cytoskeleton Eukaryotic cells are given their shape and internal organization by the cytoskeleton. Copyright Pearson Prentice Hall
  46. 46. Cytoskeleton The cytoskeleton helps the cell maintain its shape and can be involved in movement. Eukaryotic cells are given their shape and internal organization by the cytoskeleton. Copyright Pearson Prentice Hall
  47. 47. 7-3 Cell Boundaries Copyright Pearson Prentice Hall
  48. 48. 7-3 Cell Boundaries All cells are surrounded by a thin, flexible barrier known as the cell membrane. Many cells also produce a strong supporting layer around the membrane known as a cell wall. Copyright Pearson Prentice Hall
  49. 49. Cell Membrane Cell Membrane The cell membrane regulates what enters and leaves the cell and also provides protection and support. Copyright Pearson Prentice Hall
  50. 50. Cell Membrane Copyright Pearson Prentice Hall Cell Membrane Outside of cell Cell membrane Inside of cell (cytoplasm) Protein channel Proteins Carbohydrate chains Lipid bilayer
  51. 51. Cell Membrane The composition of nearly all cell membranes is a double-layered sheet called a lipid bilayer. Copyright Pearson Prentice Hall Lipid bilayer
  52. 52. Cell Membrane The lipid bilayer gives cell membranes a flexible structure that forms a barrier between the cell and its surroundings. Copyright Pearson Prentice Hall
  53. 53. Cell Membrane Most cell membranes contain protein molecules embedded in the lipid bilayer, some of which have carbohydrate molecules attached to them. Copyright Pearson Prentice Hall Protein channel Proteins Carbohydrate chains
  54. 54. Cell Walls Cell walls are found in plants, algae, fungi, and many prokaryotes. The cell wall provides support and protection for the cell. Copyright Pearson Prentice Hall
  55. 55. Cell Walls Cell Wall The cell wall lies outside the cell membrane. Most cell walls are porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily. Copyright Pearson Prentice Hall
  56. 56. Draw two eukaryotic cells PLANT CELL ANIMAL CELL Draw and label- cell wall Copyright Pearson Prentice Hall Cell wall
  57. 57. Diffusion Through Cell Boundaries Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. The cell membrane regulates movement of dissolved molecules from the liquid on one side of the membrane to the liquid on the other side. Copyright Pearson Prentice Hall
  58. 58. Diffusion Through Cell Boundaries Measuring Concentration A solution is a mixture of two or more substances. The substances dissolved in the solution are called solutes. The concentration of a solution is the mass of solute in a given volume of solution, or mass/ volume. Copyright Pearson Prentice Hall
  59. 59. Diffusion Through Cell Boundaries Diffusion– Solutes tend to move from areas of high concentration towards areas of low concentration. Copyright Pearson Prentice Hall
  60. 60. When the solute is evenly spread through the solution, the system has reached equilibrium. It will never become concentrated in one area like it was before! Copyright Pearson Prentice Hall
  61. 61. Diffusion Through Cell Boundaries ACTIVE ART go to PHSchool.com and type in Web Code cbp-3073 Copyright Pearson Prentice Hall
  62. 62. Diffusion Through Cell Boundaries There is a higher concentration of solute on one side of the membrane as compared to the other side of the membrane. Copyright Pearson Prentice Hall
  63. 63. Diffusion Through Cell Boundaries Solute particles move from the side of the membrane with a higher concentration of solute to the side of the membrane with a lower concentration of solute. The solute particles will continue to diffuse across the membrane until equilibrium is reached. Copyright Pearson Prentice Hall
  64. 64. Diffusion Through Cell Boundaries When equilibrium is reached, solute particles continue to diffuse across the membrane in both directions, but the concentrations do not change. Copyright Pearson Prentice Hall
  65. 65. Diffusion Through Cell Boundaries Diffusion depends upon random particle movements. Therefore, substances diffuse across membranes without requiring the cell to use energy. Copyright Pearson Prentice Hall
  66. 66. Osmosis Osmosis is the diffusion of water through a selectively permeable membrane. Osmosis is diffusion so it requires no energy! Copyright Pearson Prentice Hall
  67. 67. Osmosis ACTIVE ART go to PHSchool.com and type in Web Code cbp-3075 How Osmosis Works Copyright Pearson Prentice Hall Movement of water Dilute sugar solution (Water more concentrated) Concentrated sugar solution (Water less concentrated) Sugar molecules Selectively permeable membrane- only lets water through
  68. 68. Osmosis Water tends to diffuse from a highly concentrated region to a less concentrated region. If you compare two solutions, the more concentrated solution is hypertonic (“above strength”). The more dilute solution is hypotonic (“below strength”). Copyright Pearson Prentice Hall
  69. 69. Osmosis When concentrations of solutions are the same on both sides of a membrane, the solutions are isotonic (”same strength”). Copyright Pearson Prentice Hall
  70. 70. Osmosis Osmotic Pressure Osmosis exerts a pressure known as osmotic pressure on the hypertonic side of a selectively permeable membrane. Copyright Pearson Prentice Hall
  71. 71. Osmosis The cell is filled with salts, sugars, proteins, and other molecules so it is hypertonic(lots of solutes) compared to fresh water. This causes water to move into the cell. The cell becomes swollen or bursts. Copyright Pearson Prentice Hall
  72. 72. Osmosis Cells in large organisms are not in danger of bursting because they are bathed in fluids, such as blood, that are isotonic. Other cells are surrounded by tough cell walls that prevent the cells from expanding even under tremendous osmotic pressure. Copyright Pearson Prentice Hall
  73. 73. Facilitated Diffusion Facilitated Diffusion Cell membranes have protein channels that act as carriers, making it easy for certain molecules to cross. Copyright Pearson Prentice Hall
  74. 74. Facilitated Diffusion The movement of specific molecules across cell membranes through protein channels is known as facilitated diffusion. Hundreds of different protein channels have been found that allow particular substances to cross different membranes. Copyright Pearson Prentice Hall
  75. 75. Facilitated Diffusion Copyright Pearson Prentice Hall Facilitated Diffusion Protein channel Glucose molecules
  76. 76. Facilitated Diffusion Although facilitated diffusion is fast and specific, it is still diffusion. Therefore, facilitated diffusion will only occur if there is a higher concentration of the particular molecules on one side of a cell membrane as compared to the other side. Copyright Pearson Prentice Hall
  77. 77. Active Transport Active Transport Sometimes cells move materials in the opposite direction from which the materials would normally move—that is against a concentration difference. Active transport is the moving of substances against diffusion, so it requires energy. Copyright Pearson Prentice Hall
  78. 78. Active Transport Molecular Transport In active transport, small molecules and ions are carried across membranes by proteins in the membrane. Energy use in these systems enables cells to concentrate substances in a particular location, even when diffusion might move them in the opposite direction. Copyright Pearson Prentice Hall
  79. 79. ACTIVE ART go to PHSchool.com and type in Web Code cbp-3076 Copyright Pearson Prentice Hall Molecule to be carried Active Transport
  80. 80. Active Transport Endocytosis and Exocytosis Large molecules and even solid clumps of material may undergo active transport by means of the cell membrane. Endocytosis is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane. The pocket breaks loose from the outer portion of the cell membrane and forms a vacuole within the cytoplasm. Copyright Pearson Prentice Hall
  81. 81. Active Transport Two examples of endocytosis are: • phagocytosis • pinocytosis Copyright Pearson Prentice Hall
  82. 82. Active Transport In phagocytosis, extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it. Phagocytosis requires a considerable amount of energy. Copyright Pearson Prentice Hall
  83. 83. Active Transport In pinocytosis, tiny pockets form along the cell membrane, fill with liquid, and pinch off to form vacuoles within the cell. Copyright Pearson Prentice Hall
  84. 84. Active Transport Exocytosis Many cells also release large amounts of material from the cell, in a process called exocytosis. During exocytosis, the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell. Copyright Pearson Prentice Hall
  85. 85. 7-4 The Diversity of Cellular Life Copyright Pearson Prentice Hall
  86. 86. Unicellular Organisms Unicellular Organisms Unicellular organisms are made up of only one cell. Unicellular organisms dominate life on Earth. Copyright Pearson Prentice Hall
  87. 87. Multicellular Organisms Multicellular Organisms Organisms that are made up of many cells are called multicellular. There is a great variety among multicellular organisms. Copyright Pearson Prentice Hall
  88. 88. Multicellular Organisms cell specialization- cells develop differently to perform different tasks. Copyright Pearson Prentice Hall
  89. 89. Multicellular Organisms Specialized Animal Cells Animal cells are specialized in many ways. Copyright Pearson Prentice Hall
  90. 90. Multicellular Organisms Red blood cells transport oxygen. Copyright Pearson Prentice Hall
  91. 91. Multicellular Organisms Cells in the pancreas produce proteins. Copyright Pearson Prentice Hall
  92. 92. Multicellular Organisms Muscle cells allow movement. Copyright Pearson Prentice Hall
  93. 93. Multicellular Organisms Specialized Plant Cells Plants exchange carbon dioxide, oxygen, water vapor, and other gases through tiny openings called stomata on the undersides of leaves. Highly specialized cells, known as guard cells, regulate this exchange. Copyright Pearson Prentice Hall
  94. 94. Multicellular Organisms Stomata enclosed by guard cells. Copyright Pearson Prentice Hall
  95. 95. Levels of Organization Levels of Organization The levels of organization in a multicellular organism are: individual cells tissues organs organ systems Copyright Pearson Prentice Hall
  96. 96. Levels of Organization Levels of Organization Muscle cell Smooth muscle tissue Stomach Digestive system Copyright Pearson Prentice Hall
  97. 97. Levels of Organization In multicellular organisms, cells are the first level of organization. Copyright Pearson Prentice Hall
  98. 98. Levels of Organization Tissues Similar cells are grouped into units called tissues. A tissue is a group of similar cells that perform a particular function. Copyright Pearson Prentice Hall
  99. 99. Levels of Organization Copyright Pearson Prentice Hall
  100. 100. Levels of Organization Most animals have four main types of tissue: muscle epithelial nervous connective Copyright Pearson Prentice Hall
  101. 101. Levels of Organization Organs Organs are groups of tissues that work together to perform a specific function. Copyright Pearson Prentice Hall
  102. 102. Levels of Organization Organ Systems A group of organs that work together to perform a specific function is called an organ system. Copyright Pearson Prentice Hall

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