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Chapter 3

0. Chapter 3. The Molecules of Life. Biology and Society: Got Lactose?. Lactose is the main sugar found in milk. Some adults exhibit lactose intolerance, the inability to properly digest lactose. Lactose-intolerant individuals are unable to digest lactose properly.

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Chapter 3

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  1. 0 Chapter 3 The Molecules of Life Laura Coronado Bio 10 Chapter 3

  2. Biology and Society: Got Lactose? • Lactose is the main sugar found in milk. • Some adults exhibit lactose intolerance, the inability to properly digest lactose. • Lactose-intolerant individuals are unable to digest lactose properly. • Lactose is broken down by bacteria in the large intestine producing gas and discomfort. • There is no treatment for the underlying cause of lactose intolerance. • Affected people must avoid lactose-containing foods or take the enzyme lactase when eating dairy products Laura Coronado Bio 10 Chapter 3

  3. Laura Coronado Bio 10 Chapter 3 Figure 3.00

  4. ORGANIC COMPOUNDS • A cell is mostly water. • The rest of the cell consists mainly of carbon-based molecules. • Carbon forms large, complex, and diverse molecules necessary for life’s functions. • Organic compounds are carbon-based molecules. Laura Coronado Bio 10 Chapter 3

  5. Carbon Chemistry • Carbon is a versatile atom. • It has four electrons in an outer shell that holds eight. • Carbon can share its electrons with other atoms to form up to four covalent bonds. • Carbon can use its bonds to • Attach to other carbons • Form an endless diversity of carbon skeletons Animation: Carbon Skeletons Laura Coronado Bio 10 Chapter 3

  6. Double bond Carbon skeletons vary in length Carbon skeletons may have double bonds, which can vary in location Carbon skeletons may be unbranched or branched Carbon skeletons may be arranged in rings Laura Coronado Bio 10 Chapter 3 Figure 3.1

  7. Hydrocarbons • The simplest organic compounds are hydrocarbons, which are organic molecules containing only carbon and hydrogen atoms. • The simplest hydrocarbon is methane, consisting of a single carbon atom bonded to four hydrogen atoms. Laura Coronado Bio 10 Chapter 3

  8. Structural formula Ball-and-stick model Space-filling model Laura Coronado Bio 10 Chapter 3 Figure 3.2

  9. Laura Coronado Bio 10 Chapter 3 Figure 3.3

  10. Organic Molecule • Each type of organic molecule has a unique three-dimensional shape. • The shapes of organic molecules relate to their functions. • The unique properties of an organic compound depend on • Its carbon skeleton • The atoms attached to the skeleton • The groups of atoms that usually participate in chemical reactions are called functional groups. Two common examples are • Hydroxyl groups (-OH) • Carboxyl groups (C=O) Laura Coronado Bio 10 Chapter 3

  11. Giant Molecules from Smaller Building Blocks • On a molecular scale, many of life’s molecules are gigantic, earning the name macromolecules. • Three categories of macromolecules are • Carbohydrates • Proteins • Nucleic acids Laura Coronado Bio 10 Chapter 3

  12. Giant Molecules from Smaller Building Blocks • Most macromolecules are polymers. • Polymers are made by stringing together many smaller molecules called monomers. • A dehydration reaction • Links two monomers together • Removes a molecule of water Animation: Polymers Laura Coronado Bio 10 Chapter 3

  13. Short polymer Monomer Dehydration reaction Longer polymer a Building a polymer chain Laura Coronado Bio 10 Chapter 3 Figure 3.4a

  14. Hydrolysis Reaction • Organisms also have to break down macromolecules. • Hydrolysis • Breaks bonds between monomers • Adds a molecule of water • Reverses the dehydration reaction Laura Coronado Bio 10 Chapter 3

  15. Hydrolysis b Breaking a polymer chain Laura Coronado Bio 10 Chapter 3 Figure 3.4b

  16. LARGE BIOLOGICAL MOLECULES • There are four categories of large molecules in cells: • Carbohydrates • Lipids • Proteins • Nucleic acids Laura Coronado Bio 10 Chapter 3

  17. Carbohydrates • Carbohydrates are sugars or sugar polymers. They include • Small sugar molecules in soft drinks • Long starch molecules in pasta and potatoes Laura Coronado Bio 10 Chapter 3

  18. Monosaccharides • Monosaccharides are simple sugars that cannot be broken down by hydrolysis into smaller sugars. • Glucose and fructose are isomers, molecules that have the same molecular formula but different structures. • Monosaccharides are the main fuels for cellular work. • In aqueous solutions, many monosaccharides form rings. Animation: L-Dopa Laura Coronado Bio 10 Chapter 3

  19. Glucose Fructose C6H12O6 C6H12O6 Isomers Laura Coronado Bio 10 Chapter 3 Figure 3.5

  20. Fructose Glucose C6H12O6 C6H12O6 Isomers Laura Coronado Bio 10 Chapter 3 Figure 3.5a

  21. b Abbreviated ring structure a Linear and ring structures Laura Coronado Bio 10 Chapter 3 Figure 3.6

  22. Disaccharides • A disaccharide is • A double sugar • Constructed from two monosaccharides • Formed by a dehydration reaction • Disaccharides include • Lactose in milk • Maltose in beer, malted milk shakes, and malted milk ball candy • Sucrose in table sugar Animation: Disaccharides Laura Coronado Bio 10 Chapter 3

  23. Galactose Glucose Lactose Figure 3.7 Laura Coronado Bio 10 Chapter 3

  24. Disaccharides • Sucrose is • The main carbohydrate in plant sap • Rarely used as a sweetener in processed foods • High-fructose corn syrup is made by a commercial process that converts natural glucose in corn syrup to much sweeter fructose. • The United States is one of the world’s leading markets for sweeteners. • The average American consumes about 45 kg of sugar (about 100 lbs.) per year. Laura Coronado Bio 10 Chapter 3

  25. processed to extract Starch broken down into Glucose converted to sweeter Fructose added to foods as high-fructose corn syrup Ingredients: carbonated water, high-fructose corn syrup, caramel color, phosphoric acid, natural flavors Laura Coronado Bio 10 Chapter 3 Figure 3.8

  26. Polysaccharides • Polysaccharides are • Complex carbohydrates • Made of long chains of sugar units and polymers of monosaccharides • Starch is an example of a polysaccharide • Used by plant cells to store energy • Potatoes and grains are major sources of starch in the human diet. Animation: Polysaccharides Laura Coronado Bio 10 Chapter 3

  27. Glucose monomer Starch granules a Starch Glycogen granules b Glycogen Cellulose fibril Cellulose molecules c Cellulose Laura Coronado Bio 10 Chapter 3 Figure 3.9

  28. Glycogen • Glycogen is • Used by animals cells to store energy • Converted to glucose when it is needed Laura Coronado Bio 10 Chapter 3

  29. Cellulose • Cellulose • Is the most abundant organic compound on Earth • Forms cable-like fibrils in the tough walls that enclose plants • Cannot be broken apart by most animals Laura Coronado Bio 10 Chapter 3

  30. Carbohydrates in Water • Monosaccharides and disaccharides dissolve readily in water. • Cellulose does not dissolve readily in water. • Almost all carbohydrates are hydrophilic, or “water-loving,” adhering water to their surface. Laura Coronado Bio 10 Chapter 3

  31. Lipids & Fats • Lipids are • Neither macromolecules nor polymers • Hydrophobic, unable to mix with water • A typical fat, or triglyceride, consists of a glycerol molecule joined with three fatty acid molecules via a dehydration reaction. • Essential functions in the human body including • Energy storage • Cushioning • Insulation Laura Coronado Bio 10 Chapter 3

  32. Oil (hydrophobic) Vinegar (hydrophilic) Figure 3.10 Laura Coronado Bio 10 Chapter 3

  33. Fatty acid Glycerol (a) A dehydration reaction linking a fatty acid to glycerol (b) A fat molecule with a glycerol “head” and three energy-rich hydrocarbon fatty acid “tails” Laura Coronado Bio 10 Chapter 3 Figure 3.11

  34. Fatty Acid • If the carbon skeleton of a fatty acid has • Fewer than the maximum number of hydrogens, it is unsaturated • The maximum number of hydrogens, then it is saturated • A saturated fat has no double bonds, and all three of its fatty acids are saturated. Laura Coronado Bio 10 Chapter 3

  35. Lipids & Fats • Most plant oils tend to be low in saturated fatty acids and liquid at room temperature. • Most animal fats • Have a high proportion of saturated fatty acids • Can easily stack, tending to be solid at room temperature • Contribute to atherosclerosis, a condition in which lipid-containing plaques build up within the walls of blood vessels Laura Coronado Bio 10 Chapter 3

  36. Hydrogenation • Hydrogenation • Adds hydrogen • Converts unsaturated fats to saturated fats • Makes liquid fats solid at room temperature • Creates trans fat, a type of unsaturated fat that is even less healthy than saturated fats Laura Coronado Bio 10 Chapter 3

  37. TYPES OF FATS Saturated Fats Unsaturated Fats Margarine INGREDIENTS: SOYBEAN OIL, FULLY HYDROGENATED COTTONSEED OIL, PARTIALLY HYDROGENATED COTTONSEED OIL AND SOYBEAN OILS, MONO AND DIGLYCERIDES, TBHO AND CITRIC ACID ANTIOXIDANTS Trans fats Omega-3 fats Plant oils Laura Coronado Bio 10 Chapter 3 Figure 3.12

  38. Unsaturated Fats Margarine INGREDIENTS: SOYBEAN OIL, FULLY HYDROGENATED COTTONSEED OIL, PARTIALLY HYDROGENATED COTTONSEED OIL AND SOYBEAN OILS, MONO AND DIGLYCERIDES, TBHO AND CITRIC ACID ANTIOXIDANTS Trans fats Omega-3 fats Plant oils Laura Coronado Bio 10 Chapter 3 Figure 3.12b

  39. Steroids • Steroids are very different from fats in structure and function. • The carbon skeleton is bent to form four fused rings. • Steroids vary in the functional groups attached to this core set of rings. • Cholesterol • A key component of cell membranes • The “base steroid” from which your body produces other steroids, such as estrogen and testosterone Laura Coronado Bio 10 Chapter 3

  40. Cholesterol Testosterone A type of estrogen Laura Coronado Bio 10 Chapter 3 Figure 3.13

  41. Steroids • Synthetic anabolic steroids • Resemble testosterone • Mimic some of its effects • Can cause serious physical and mental problems • Are abused by athletes to enhance performance Laura Coronado Bio 10 Chapter 3

  42. THG Laura Coronado Bio 10 Chapter 3 Figure 3.14

  43. Proteins • Proteins • Are polymers constructed from amino acid monomers • Perform most of the tasks the body needs to function • Form enzymes, chemicals that change the rate of a chemical reaction without being changed in the process Laura Coronado Bio 10 Chapter 3

  44. MAJOR TYPES OF PROTEINS Contractile Proteins Transport Proteins Enzymes Structural Proteins Storage Proteins Laura Coronado Bio 10 Chapter 3 Figure 3.15

  45. The Monomers of Proteins: Amino Acids • All proteins are constructed from a common set of 20 kinds of amino acids. • Each amino acid consists of a central carbon atom bonded to four covalent partners in which three of those attachment groups are common to all amino acids. Laura Coronado Bio 10 Chapter 3

  46. Amino group Carboxyl group Side group a The general structure of an amino acid Hydrophobic side group Hydrophilic side group Leucine Serine b Examples of amino acids with hydrophobic and hydrophilic side groups Laura Coronado Bio 10 Chapter 3 Figure 3.16

  47. Proteins as Polymers • Cells link amino acids together by dehydration reactions, forming peptide bonds and creating long chains of amino acids called polypeptides. • Your body has tens of thousands of different kinds of protein. • Proteins differ in their arrangement of amino acids. • The specific sequence of amino acids in a protein is its primary structure. Laura Coronado Bio 10 Chapter 3

  48. Carboxyl group Amino group Side group Side group Amino acid Amino acid Dehydration reaction Side group Side group Peptide bond Laura Coronado Bio 10 Chapter 3 Figure 3.17-2

  49. 15 5 1 10 30 35 20 25 45 40 50 55 65 60 70 85 80 75 Amino acid 95 90 100 110 115 105 125 120 129 Laura Coronado Bio 10 Chapter 3 Figure 3.18

  50. SEM 7. . . 146 6 5 1 2 3 4 Normal red blood cell Normal hemoglobin a Normal hemoglobin SEM 7. . . 146 6 1 5 2 3 4 Sickled red blood cell Sickle-cell hemoglobin b Sickle-cell hemoglobin Laura Coronado Bio 10 Chapter 3 Figure 3.19

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