1. Molecules of Life
Chapter 3 Part 1

2. Impacts, Issues: Fear of Frying
Trans fats in hydrogenated vegetable oil raise levels of cholesterol in our blood more than any other fat, and directly alter blood vessel function

3. Organic Molecules All molecules of life are built with carbon atoms
We can use different models to highlight different aspects of the same molecule

4. 3.1 Carbon – The Stuff of Life
Organic molecules are complex molecules of life, built on a framework of carbon atoms
Carbohydrates
Lipids
Proteins
Nucleic acids

5. Carbon – The Stuff of Life
Carbon atoms can be assembled and remodeled into many organic compounds
Can bond with one, two, three, or four atoms
Can form polar or nonpolar bonds
Can form chains or rings

6. Carbon Rings

7. Representing Structures of Organic Molecules
Structural model of an organic molecule
Each line is a covalent bond; two lines are double bonds; three lines are triple bonds

8. Representing Structures of Organic Molecules
Carbon ring structures are represented as polygons; carbon atoms are implied

9. Representing Structures of Organic Molecules
Ball-and-stick models show positions of atoms in three dimensions; elements are coded by color

10. Representing Structures of Organic Molecules
Space-filling models show how atoms sharing electrons overlap

11. Three Models of a Hemoglobin Molecule

12. Figure 3.3
Visualizing the structure of hemoglobin, the oxygen-transporting molecule in red blood cells (top left). Models that show individual atoms usually depict them color-coded by element. Other models may be shown in various colors, depending on which features are highlighted.
Fig. 3-3 (top), p. 37

13. Figure 3.3
Visualizing the structure of hemoglobin, the oxygen-transporting molecule in red blood cells (top left). Models that show individual atoms usually depict them color-coded by element. Other models may be shown in various colors, depending on which features are highlighted.
red blood cell
Fig. 3-3 (top), p. 37

14. A A space-filling model of hemoglobin shows the
Figure 3.3
Visualizing the structure of hemoglobin, the oxygen-transporting molecule in red blood cells (top left). Models that show individual atoms usually depict them color-coded by element. Other models may be shown in various colors, depending on which features are highlighted.
A A space-filling model of hemoglobin shows the
complexity of the molecule.
Fig. 3-3a, p. 37

15. Figure 3.3
Visualizing the structure of hemoglobin, the oxygen-transporting molecule in red blood cells (top left). Models that show individual atoms usually depict them color-coded by element. Other models may be shown in various colors, depending on which features are highlighted.
B A surface model of the same molecule reveals crevices and folds that are important for its function. Heme groups, in red, are cradled in pockets of the molecule.
Fig. 3-3b, p. 37

16. Figure 3.3
Visualizing the structure of hemoglobin, the oxygen-transporting molecule in red blood cells (top left). Models that show individual atoms usually depict them color-coded by element. Other models may be shown in various colors, depending on which features are highlighted.
C A ribbon model of hemoglobin shows all four heme groups, also in red, held in place by the molecule’s coils.
Fig. 3-3c, p. 37

17. 3.2 From Structure to Function
The function of organic molecules in biological systems begins with their structure
The building blocks of carbohydrates, lipids, proteins, and nucleic acids bond together in different arrangements to form different kinds of complex molecules

18. Functional Groups Hydrocarbon
An organic molecule that consists only of hydrogen and carbon atoms
Most biological molecules have at least one functional group
A cluster of atoms that imparts specific chemical properties to a molecule (polarity, acidity)

19. Common Functional Groups in Biological Molecules

20. Figure 3.4
Common functional groups in biological molecules, with examples of where they occur. Because such groups impart specific chemical characteristics to organic compounds, they are an important part of why the molecules of life function as they do.
Stepped Art
Fig. 3-4, p. 38

21. Animation: Functional group

22. Effects of Functional Groups: Sex Hormones

23. Figure 3.5
Estrogen and testosterone, sex hormones that cause differences in traits between males and females of many species such as wood ducks (Aix sponsa).
Figure It Out: Which functional groups differ between these hormones?
Answer: The hydroxyl and carbonyl groups differ in position, and testosterone has an extra methyl group.
Fig. 3-5a, p. 38

24. one of the estrogens testosterone Figure 3.5
Estrogen and testosterone, sex hormones that cause differences in traits between males and females of many species such as wood ducks (Aix sponsa).
Figure It Out: Which functional groups differ between these hormones?
Answer: The hydroxyl and carbonyl groups differ in position, and testosterone has an extra methyl group.
one of the estrogens
testosterone
Fig. 3-5a, p. 38

25. Figure 3.5
Estrogen and testosterone, sex hormones that cause differences in traits between males and females of many species such as wood ducks (Aix sponsa).
Figure It Out: Which functional groups differ between these hormones?
Answer: The hydroxyl and carbonyl groups differ in position, and testosterone has an extra methyl group.
Fig. 3-5b, p. 38

26. female wood duck male wood duck
Figure 3.5
Estrogen and testosterone, sex hormones that cause differences in traits between males and females of many species such as wood ducks (Aix sponsa).
Figure It Out: Which functional groups differ between these hormones?
Answer: The hydroxyl and carbonyl groups differ in position, and testosterone has an extra methyl group.
Fig. 3-5b, p. 38

27. What Cells Do to Organic Compounds
Metabolism
Activities by which cells acquire and use energy to construct, rearrange, and split organic molecules
Allows cells to live, grow, and reproduce
Requires enzymes (proteins that increase the speed of reactions)

28. What Cells Do to Organic Compounds
Condensation
Covalent bonding of two molecules to form a larger molecule
Water forms as a product
Hydrolysis
The reverse of condensation
Cleavage reactions split larger molecules into smaller ones
Water is split

29. What Cells Do to Organic Compounds
Monomers
Molecules used as subunits to build larger molecules (polymers)
Polymers
Larger molecules that are chains of monomers
May be split and used for energy

30. What Cells Do to Organic Compounds

31. Condensation and Hydrolysis

32. Figure 3.6
Two examples of what happens to the organic molecules in cells. (a) In condensation, two molecules are covalently bonded into a larger one. (b) In hydrolysis, a water-requiring cleavage reaction splits a larger molecule into two smaller molecules.
A) Condensation. An —OH group from one molecule combines with an H atom from another. Water forms as the two molecules bond covalently.
B) Hydrolysis. A molecule splits, then an —OH group and an H atom from a water molecule become attached to sites exposed by the reaction.
Stepped Art
Fig. 3-6, p. 39

33. Animation: Condensation and hydrolysis

34. 3.1-3.2 Key Concepts: Structure Dictates Function
We define cells partly by their capacity to build complex carbohydrates and lipids, proteins, and nucleic acids
All of these organic compounds have functional groups attached to a backbone of carbon atoms

35. 3.3 Carbohydrates
Carbohydrates are the most plentiful biological molecules in the biosphere
Cells use some carbohydrates as structural materials; others for stored or instant energy

36. Carbohydrates Carbohydrates
Organic molecules that consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio
Three types of carbohydrates in living systems
Monosaccharides
Oligosaccharides
Polysaccharides

37. Simple Sugars
Monosaccharides (one sugar unit) are the simplest carbohydrates
Used as an energy source or structural material
Backbones of 5 or 6 carbons
Example: glucose

38. Short-Chain Carbohydrates
Oligosaccharides
Short chains of monosaccharides
Example: sucrose, a disaccharide

39. glucose + fructose sucrose + water Figure 3.7
The synthesis of a sucrose molecule is an example of a condensation reaction. You are already familiar with sucrose—it is common table sugar.
Fig. 3-7b, p. 40

40. glucose + fructose sucrose + water Figure 3.7
The synthesis of a sucrose molecule is an example of a condensation reaction. You are already familiar with sucrose—it is common table sugar.
Stepped Art
Fig. 3-7b, p. 40

41. Complex Carbohydrates
Polysaccharides
Straight or branched chains of many sugar monomers
The most common polysaccharides are cellulose, starch, and glycogen
All consist of glucose monomers
Each has a different pattern of covalent bonding, and different chemical properties

42. Cellulose, Starch, and Glycogen

43. Figure 3.8
Structure of (a) cellulose, (b) starch, and (c) glycogen, and their typical locations in a few organisms. All three carbohydrates consist only of glucose units, but the different bonding patterns that link the subunits result in substances with very different properties.
Fig. 3-8a, p. 41

44. Figure 3.8
Structure of (a) cellulose, (b) starch, and (c) glycogen, and their typical locations in a few organisms. All three carbohydrates consist only of glucose units, but the different bonding patterns that link the subunits result in substances with very different properties.
Fig. 3-8b, p. 41

45. Figure 3.8
Structure of (a) cellulose, (b) starch, and (c) glycogen, and their typical locations in a few organisms. All three carbohydrates consist only of glucose units, but the different bonding patterns that link the subunits result in substances with very different properties.
Fig. 3-8c, p. 41

46. Chitin
Chitin
A nitrogen-containing polysaccharide that strengthens hard parts of animals such as crabs, and cell walls of fungi

47. 3.3 Key Concepts: Carbohydrates
Carbohydrates are the most abundant biological molecules
They function as energy reservoirs and structural materials
Different types of complex carbohydrates are built from the same subunits of simple sugars, bonded in different patterns

48. 3.4 Greasy, Oily – Must Be Lipids
Lipids function as the body’s major energy reservoir, and as the structural foundation of cell membranes
Lipids
Fatty, oily, or waxy organic compounds that are insoluble in water

49. Fatty Acids Many lipids incorporate fatty acids
Simple organic compounds with a carboxyl group joined to a backbone of 4 to 36 carbon atoms
Essential fatty acids are not made by the body and must come from food
Omega-3 and omega-6 fatty acids

50. Fatty Acids
Saturated, monounsaturated, polyunsaturated

51. stearic acid oleic acid linolenic acid Figure 3.10
Examples of fatty acids. (a) The backbone of stearic acid is fully saturated with hydrogen atoms. (b) Oleic acid, with a double bond in its backbone, is unsaturated. (c) Linolenic acid, also unsaturated, has three double bonds. The first double bond occurs at the third carbon from the end of the tail, so oleic acid is called an omega-3 fatty acid. Omega-3 and omega-6 fatty acids are “essential fatty acids.” Your body does not make them, so they must come from food.
stearic acid
oleic acid
linolenic acid
Fig. 3-10, p. 42

52. Fats Fats Triglycerides
Lipids with one, two, or three fatty acids “tails” attached to glycerol
Triglycerides
Neutral fats with three fatty acids attached to glycerol
The most abundant energy source in vertebrates
Concentrated in adipose tissues (for insulation and cushioning)

53. Triglycerides

54. triglyceride, a neutral fat
glycerol
+ 3H2O
Figure 3.11
Triglyceride formation by the condensation of three fatty acids with one glycerol molecule. The photograph shows triglyceride-insulated emperor penguins during an Antarctic blizzard.
triglyceride, a neutral fat
three fatty acid tails
Fig. 3-11a, p. 42

55. Figure 3.11
Triglyceride formation by the condensation of three fatty acids with one glycerol molecule. The photograph shows triglyceride-insulated emperor penguins during an Antarctic blizzard.
Fig. 3-11b, p. 42

56. Animation: Triglyceride formation

57. Saturated and Unsaturated Fats
Saturated fats (animal fats)
Fatty acids with only single covalent bonds
Pack tightly; solid at room temperature
Unsaturated fats (vegetable oils)
Fatty acids with one or more double bonds
Kinked; liquid at room temperature

58. Trans Fats
Trans fats
Partially hydrogenated vegetable oils formed by a chemical hydrogenation process
Double bond straightens the molecule
Pack tightly; solid at room temperature

59. Cis and Trans Fatty Acids

60. cis double bond a oleic acid Figure 3.12
The only difference between (a) oleic acid (a cis fatty acid) and (b) elaidic acid (a trans fatty acid) is the arrangement of hydrogens around one double bond. Trans fatty acids form during chemical hydrogenation processes.
a oleic acid
Fig. 3-12a, p. 43

61. trans double bond b elaidic acid Figure 3.12
The only difference between (a) oleic acid (a cis fatty acid) and (b) elaidic acid (a trans fatty acid) is the arrangement of hydrogens around one double bond. Trans fatty acids form during chemical hydrogenation processes.
b elaidic acid
Fig. 3-12b, p. 43

62. Phospholipids Phospholipids
Molecules with a polar head containing a phosphate and two nonpolar fatty acid tails
Heads are hydrophilic, tails are hydrophobic
The most abundant lipid in cell membranes

63. Phospholipids

64. Figure 3.13
Phospholipid, (a) structure and (b) icon. Phospholipids are the main structural component of all cell membranes (c).
Fig. 3-13a, p. 43

65. hydrophilic head two hydrophobic tails Figure 3.13
Phospholipid, (a) structure and (b) icon. Phospholipids are the main structural component of all cell membranes (c).
Fig. 3-13b, p. 43

66. c Cell membrane section
Figure 3.13
Phospholipid, (a) structure and (b) icon. Phospholipids are the main structural component of all cell membranes (c).
c Cell membrane section
Fig. 3-13c, p. 43

67. Waxes
Waxes
Complex mixtures with long fatty-acid tails bonded to long-chain alcohols or carbon rings
Protective, water-repellant covering

68. Cholesterol and Other Steroids
Lipids with a rigid backbone of four carbon rings and no fatty-acid tails
Cholesterol
Component of eukaryotic cell membranes
Remodeled into bile salts, vitamin D, and steroid hormones (estrogens and testosterone)

69. Cholesterol

70. 3.4 Key Concepts: Lipids
Lipids function as energy reservoirs and waterproofing or lubricating substances
Some are remodeled into other substances
Lipids are the main structural components of cell membranes

71. Animation: Sucrose synthesis

72. Animation: Cholesterol

73. Animation: Fatty acids

74. Animation: Molecular models of the protein hemoglobin

75. Animation: Phospholipid structure

76. Animation: Secondary and tertiary structure

77. Animation: Structure of an amino acid

78. Animation: Structure of ATP

79. Animation: Structure of starch and cellulose

80. Animation: Sucrose synthesis