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  1. 1. Biology and Society: Does Thanksgiving Dinner Make You Sleepy? <ul><ul><li>After finishing a huge Thanksgiving dinner, many people feel especially lethargic and a few even doze off. </li></ul></ul><ul><ul><li>Many people think that turkey makes you sleepy. </li></ul></ul><ul><ul><ul><li>Is there a biological basis to this claim? </li></ul></ul></ul>Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  2. 2. <ul><ul><li>Turkey meat is high in tryptophan. </li></ul></ul><ul><ul><li>Tryptophan is a molecule that is converted in your body to serotonin, which promotes sleep. </li></ul></ul>Figure 3.1 <ul><ul><li>However, there is little evidence that a turkey dinner encourages sleep more than any other meal. </li></ul></ul>
  3. 3. Organic Molecules <ul><ul><li>A cell is mostly water. </li></ul></ul><ul><ul><ul><li>The rest of the cell consists mostly of carbon-based molecules. </li></ul></ul></ul><ul><ul><ul><li>Organic chemistry is the study of carbon compounds. </li></ul></ul></ul>
  4. 4. Carbon Chemistry <ul><ul><li>Carbon is a versatile atom. </li></ul></ul><ul><ul><ul><li>It has four electrons in an outer shell that holds eight. </li></ul></ul></ul><ul><ul><ul><li>Carbon can share its electrons with other atoms to form up to four covalent bonds. </li></ul></ul></ul>
  5. 5. <ul><ul><li>Carbon can use its bonds to </li></ul></ul><ul><ul><ul><li>Attach to other carbons </li></ul></ul></ul><ul><ul><ul><li>Form an endless diversity of carbon skeletons </li></ul></ul></ul>Figure 3.2
  6. 6. <ul><ul><li>The simplest organic compounds are hydrocarbons. </li></ul></ul><ul><ul><ul><li>These are organic molecules containing only carbon and hydrogen atoms. </li></ul></ul></ul><ul><ul><ul><li>The simplest hydrocarbon is methane. </li></ul></ul></ul>Figure 3.3
  7. 7. <ul><ul><li>Larger hydrocarbons are the main molecules in the gasoline we burn in our cars. </li></ul></ul>Figure 3.4 <ul><ul><li>The hydrocarbons of fat molecules provide energy for our bodies. </li></ul></ul>
  8. 8. Figure 3.5
  9. 9. Giant Molecules from Smaller Building Blocks <ul><ul><li>On a molecular scale, many of life’s molecules are gigantic. </li></ul></ul><ul><ul><ul><li>Biologists call them macromolecules. </li></ul></ul></ul><ul><ul><ul><li>Examples: DNA, carbohydrates </li></ul></ul></ul>
  10. 10. <ul><ul><li>Most macromolecules are polymers. </li></ul></ul><ul><ul><ul><li>Polymers are made by stringing together many smaller molecules called monomers. </li></ul></ul></ul><ul><ul><ul><li>Cells link monomers by dehydration reactions. </li></ul></ul></ul>Figure 3.6a
  11. 11. <ul><ul><li>Organisms also have to break down macromolecules. </li></ul></ul><ul><ul><ul><li>Cells do this by a process called hydrolysis. </li></ul></ul></ul>Figure 3.6b
  12. 12. Biological Molecules <ul><ul><li>There are four categories of large molecules in cells: </li></ul></ul><ul><ul><ul><li>Carbohydrates </li></ul></ul></ul><ul><ul><ul><li>Lipids </li></ul></ul></ul><ul><ul><ul><li>Proteins </li></ul></ul></ul><ul><ul><ul><li>Nucleic acids </li></ul></ul></ul>
  13. 13. Carbohydrates <ul><ul><li>Carbohydrates include: </li></ul></ul><ul><ul><ul><li>Small sugar molecules in soft drinks </li></ul></ul></ul><ul><ul><ul><li>Long starch molecules in pasta and potatoes </li></ul></ul></ul>
  14. 14. Monosaccharides <ul><ul><li>Monosaccharides are simple sugars. </li></ul></ul><ul><ul><ul><li>Glucose is found in sports drinks. </li></ul></ul></ul><ul><ul><ul><li>Fructose is found in fruit. </li></ul></ul></ul><ul><ul><li>Honey contains both glucose and fructose. </li></ul></ul>
  15. 15. <ul><ul><li>The monosaccharides glucose and fructose are isomers. </li></ul></ul><ul><ul><ul><li>They have the same formula, but their atoms are arranged differently. </li></ul></ul></ul>Figure 3.8
  16. 16. <ul><ul><li>In aqueous solutions, monosaccharides form rings. </li></ul></ul><ul><ul><li>Monosaccharides are the main fuel that cells use for cellular work. </li></ul></ul>Figure 3.9
  17. 17. Disaccharides <ul><ul><li>A disaccharide is a double sugar. </li></ul></ul><ul><ul><ul><li>It is constructed from two monosaccharides. </li></ul></ul></ul><ul><ul><li>Disaccharides are joined through a dehydration reaction. </li></ul></ul>Figure 3.10
  18. 18. <ul><ul><li>Lactose is another type of disaccharide. </li></ul></ul><ul><ul><ul><li>Some people have trouble digesting lactose, a condition called lactose intolerance. </li></ul></ul></ul>Figure 3.11
  19. 19. <ul><ul><li>The most common disaccharide is sucrose, common table sugar. </li></ul></ul><ul><ul><ul><li>It consists of a glucose linked to a fructose. </li></ul></ul></ul><ul><ul><ul><li>Sucrose is extracted from sugar cane and the roots of sugar beets. </li></ul></ul></ul><ul><ul><li>The United States is one of the world’s leading markets for sweeteners. </li></ul></ul><ul><ul><ul><li>The average American consumes about 64 kg of sugar per year. </li></ul></ul></ul>
  20. 20. <ul><ul><li>Complex carbohydrates are called polysaccharides. </li></ul></ul><ul><ul><ul><li>They are long chains of sugar units. </li></ul></ul></ul><ul><ul><ul><li>They are polymers of monosaccharides. </li></ul></ul></ul>Figure 3.13
  21. 21. <ul><ul><ul><li>Grazing animals survive on a diet of cellulose because they have prokaryotes in their digestive tracts that can break down cellulose. </li></ul></ul></ul>Figure 3.14
  22. 22. <ul><ul><li>Simple sugars and double sugars dissolve readily in water. </li></ul></ul><ul><ul><ul><li>They are hydrophilic, or “water-loving.” </li></ul></ul></ul>
  23. 23. <ul><li>In aqueous solutions, _____________ form ring structures. </li></ul><ul><li>Name three different polysaccharides. </li></ul>
  24. 24. <ul><li>In aqueous solutions, _monosaccharides_ form ring structures. </li></ul><ul><li>Name three different polysaccharides. </li></ul>
  25. 25. <ul><li>In aqueous solutions, _monosaccharides_ form ring structures. </li></ul><ul><li>Name three different polysaccharides. </li></ul><ul><li>Starch – form of energy storage in plants </li></ul><ul><li>Glycogen – form of energy storage in animals </li></ul><ul><li>Celluose – structural component of plant cells </li></ul>
  26. 26. Lipids <ul><ul><li>Lipids are hydrophobic. </li></ul></ul><ul><ul><ul><li>They do not mix with water. </li></ul></ul></ul><ul><ul><ul><li>Examples: fats and steroids </li></ul></ul></ul>
  27. 27. Fats <ul><ul><li>Dietary fat consists largely of the molecule triglyceride. </li></ul></ul><ul><ul><ul><li>Triglyceride is a combination of glycerol and three fatty acids. </li></ul></ul></ul>
  28. 28. <ul><ul><li>Unsaturated fatty acids </li></ul></ul><ul><ul><ul><li>Have less than the maximum number of hydrogens bonded to the carbons. </li></ul></ul></ul><ul><ul><li>Saturated fatty acids </li></ul></ul><ul><ul><ul><li>Have the maximum number of hydrogens bonded to the carbons. </li></ul></ul></ul>Figure 3.15b
  29. 29. <ul><ul><li>Most animal fats have a high proportion of saturated fatty acids, which can be unhealthy. </li></ul></ul><ul><ul><ul><li>Example: butter </li></ul></ul></ul><ul><ul><li>Most plant oils tend to be low in saturated fatty acids. </li></ul></ul><ul><ul><ul><li>Example: corn oil </li></ul></ul></ul>
  30. 30. <ul><ul><li>Not all fats are unhealthy. Some fats perform important functions in the body and are essential to a healthy diet. </li></ul></ul>Figure 3.16
  31. 31. Steroids <ul><ul><li>Steroids are very different from fats in structure and function. </li></ul></ul><ul><ul><ul><li>The carbon skeleton is bent to form four fused rings. </li></ul></ul></ul><ul><ul><li>Cholesterol is the “base steroid” from which your body produces other steroids. </li></ul></ul><ul><ul><ul><li>Example: sex hormones </li></ul></ul></ul>
  32. 32. Steroids Figure 3.17
  33. 33. Proteins Figure 3.19
  34. 34. The Monomers: Amino Acids <ul><ul><li>All proteins are constructed from a common set of 20 kinds of amino acids. </li></ul></ul>
  35. 35. <ul><ul><li>Each amino acid consists of </li></ul></ul><ul><ul><ul><li>A central carbon atom bonded to four covalent partners. </li></ul></ul></ul><ul><ul><ul><li>A side group that is variable among all 20. </li></ul></ul></ul>Figure 3.20
  36. 36. <ul><ul><li>Cells link amino acids together by dehydration reactions. </li></ul></ul><ul><ul><ul><li>The resulting bond between them is called a peptide bond . </li></ul></ul></ul>Figure 3.21
  37. 37. <ul><ul><li>Primary structure = The specific sequence of amino acids in a protein </li></ul></ul>Figure 3.22 <ul><ul><li>A slight change in the primary structure of a protein affects its ability to function. </li></ul></ul>
  38. 38. <ul><ul><ul><li>The substitution of one amino acid for another in hemoglobin causes sickle-cell disease. </li></ul></ul></ul>Figure 3.23
  39. 39. <ul><ul><li>Proteins have four levels of structure. </li></ul></ul>Figure 3.24
  40. 40. What Determines Protein Structure? <ul><ul><li>A protein’s shape is sensitive to the surrounding environment. </li></ul></ul><ul><ul><ul><li>Unfavorable temperature and pH changes can cause a protein to unravel and lose its shape. </li></ul></ul></ul><ul><ul><ul><li>This is called denaturation. </li></ul></ul></ul>
  41. 41. <ul><li>What type of biological molecules are hydrophillic? Hydrophobic? </li></ul><ul><li>What are the “building blocks” of proteins? </li></ul>
  42. 42. <ul><li>What type of biological molecules are hydrophillic? Hydrophobic? </li></ul><ul><li>Hydrophillic: simple sugars and double sugars </li></ul><ul><li>Hydrophobic: lipids such as fat and cholesterol </li></ul><ul><li>What are the “building blocks” of proteins? </li></ul>
  43. 43. <ul><li>What type of biological molecules are hydrophillic? Hydrophobic? </li></ul><ul><li>Hydrophillic: simple sugars and double sugars </li></ul><ul><li>Hydrophobic: lipids such as fat and cholesterol </li></ul><ul><li>What are the “building blocks” of proteins? </li></ul><ul><li>Amino Acids </li></ul>
  44. 44. Nucleic Acids <ul><ul><li>Nucleic acids are information storage molecules. </li></ul></ul><ul><ul><ul><li>They provide the directions for building proteins. </li></ul></ul></ul>
  45. 45. <ul><ul><li>There are two types of nucleic acids: </li></ul></ul><ul><ul><ul><li>DNA, deoxyribonucleic acid </li></ul></ul></ul><ul><ul><ul><li>RNA, ribonucleic acid </li></ul></ul></ul>
  46. 46. Figure 3.25
  47. 47. Figure 3.26 A Nucleotide:
  48. 48. <ul><ul><li>Each DNA nucleotide has one of the following bases: </li></ul></ul>Figure 3.27
  49. 49. Figure 3.28a
  50. 50. <ul><ul><li>Two strands of DNA join together to form a double helix. </li></ul></ul>Figure 3.28b
  51. 51. <ul><ul><li>RNA, ribonucleic acid, is different from DNA. </li></ul></ul><ul><ul><ul><li>Its sugar has an extra OH group. </li></ul></ul></ul><ul><ul><ul><li>It has the base uracil (U) instead of thymine (T). </li></ul></ul></ul>
  52. 52. DNA and Proteins as Evolutionary Tape Measures <ul><ul><li>Evolutionary relationships between organisms can be assessed. </li></ul></ul><ul><ul><ul><li>Molecular genealogy extends to relationships between species. </li></ul></ul></ul><ul><ul><ul><li>Biologists use molecular analysis of DNA and protein sequences for testing evolutionary hypotheses. </li></ul></ul></ul>Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  53. 53. Figure 3.30
  54. 54. The Microscopic World of Cells <ul><ul><li>Organisms are either: </li></ul></ul><ul><ul><ul><li>Single-celled, such as most bacteria and protists </li></ul></ul></ul><ul><ul><ul><li>Multicelled, such as plants, animals, and most fungi </li></ul></ul></ul>
  55. 55. <ul><ul><li>The light microscope is used by many scientists. </li></ul></ul><ul><ul><ul><li>Light passes through the specimen. </li></ul></ul></ul><ul><ul><ul><li>Lenses enlarge, or magnify, the image. </li></ul></ul></ul>Figure 4.2a
  56. 56. <ul><ul><li>Cells were first discovered in 1665 by Robert Hooke. </li></ul></ul><ul><ul><li>The accumulation of scientific evidence led to the cell theory: </li></ul></ul><ul><ul><ul><li>All living things are composed of cells. </li></ul></ul></ul><ul><ul><ul><li>All cells are formed from previously existing cells. </li></ul></ul></ul>
  57. 57. <ul><ul><li>The electron microscope (EM) uses a beam of electrons. </li></ul></ul><ul><ul><ul><li>It has a higher resolving power than the light microscope. </li></ul></ul></ul><ul><ul><li>The electron microscope can magnify up to 100,000X. </li></ul></ul><ul><ul><ul><li>Such power reveals the diverse parts within a cell. </li></ul></ul></ul>Figure 4.3
  58. 58. <ul><ul><li>The scanning electron microscope (SEM) is used to study the detailed architecture of the surface of a cell. </li></ul></ul>Figure 4.2b
  59. 59. <ul><ul><li>The transmission electron microscope (TEM) is useful for exploring the internal structure of a cell. </li></ul></ul>Figure 4.2c
  60. 60. The Two Major Categories of Cells <ul><ul><li>The countless cells on earth fall into two categories: </li></ul></ul><ul><ul><ul><li>Prokaryotic cells </li></ul></ul></ul><ul><ul><ul><li>Eukaryotic cells </li></ul></ul></ul><ul><ul><li>Prokaryotic and eukaryotic cells differ in several respects. </li></ul></ul>
  61. 61. Figure 4.4
  62. 62. Figure 4.5
  63. 63. Figure 4.6a
  64. 64. Figure 4.6b