1. Lecture Outlines by Gregory Ahearn, University of North Florida Copyright © 2011 Pearson Education Inc. Chapter 3 Biological Molecules

2. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Chapter 3 At a Glance  3.1 Why Is Carbon So Important in Biological Molecules?  3.2 How Are Organic Molecules Synthesized?  3.3 What Are Carbohydrates?  3.4 What Are Lipids?  3.5 What Are Proteins?  3.6 What Are Nucleotides and Nucleic Acids?

3. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.1 Why Is Carbon So Important in Biological Molecules?  Organic/inorganic molecules and functional groups –Organic refers to molecules containing a carbon skeleton bonded to hydrogen atoms –Inorganic refers to carbon dioxide and all molecules without carbon

4. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.1 Why Is Carbon So Important in Biological Molecules?  Organic/inorganic molecules and functional groups (continued) –The carbon atom is versatile because it has four electrons in an outermost shell that can accommodate eight electrons –Therefore, a carbon atom can become stable by forming up to four bonds (single, double, or triple) –As a result, organic molecules can assume complex shapes, including branched chains, rings, sheets, and helices

5. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.1 Why Is Carbon So Important in Biological Molecules?  Functional groups in organic molecules determine the characteristics and chemical reactivity of the molecules –Functional groups are less stable than the carbon backbone and are more likely to participate in chemical reactions

6. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Table 3-1

7. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.2 How Are Organic Molecules Synthesized? –Small organic molecules (called monomers) are joined to form longer molecules (called polymers) –Biomolecules are joined or broken through dehydration synthesis or hydrolysis

8. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.2 How Are Organic Molecules Synthesized?  Monomers are joined together through dehydration synthesis, at the site where an H and an OH are removed, resulting in the loss of a water molecule (H 2 O)  The openings in the outer electron shells of the two subunits are filled when the two subunits share electrons, creating a covalent bond

9. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Monomers and Polymers

10. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Dehydration Synthesis Fig. 3-1 dehydration synthesis  

11. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.2 How Are Organic Molecules Synthesized?  Polymers are broken apart through hydrolysis (“water cutting”) –Water is broken into H and OH and is used to break the bond between monomers

12. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Hydrolysis

13. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Hydrolysis Fig. 3-2  hydrolysis

14. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.2 How Are Organic Molecules Synthesized?  All biological molecules fall into one of four categories –Carbohydrates –Lipids –Proteins –Nucleotides/nucleic acids

15. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Table 3-2 (1 of 2)

16. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Table 3-2 (2 of 2)

17. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Carbohydrate molecules are composed of C, H, and O in the ratio of 1:2:1 –If a carbohydrate consists of just one sugar molecule, it is a monosaccharide –Two linked monosaccharides form a disaccharide –A polymer of many monosaccharides is a polysaccharide

18. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Carbohydrates are important energy sources for most organisms  Most small carbohydrates are water-soluble due to the polar OH functional group

19. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  There are several monosaccharides with slightly different structures –The basic monosaccharide structure is: –A backbone of 3–7 carbon atoms –Most of the carbon atoms have both a hydrogen (-H) and an hydroxyl group (-OH) attached to them –Most carbohydrates have the approximate chemical formula (CH 2 O) n where “n” is the number of carbons in the backbone –When dissolved in the cytoplasmic fluid of a cell, the carbon backbone usually forms a ring

20. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  There are several monosaccharides with slightly different structures (continued) –Example monosaccharides –Glucose (C 6 H 12 O 6 ): the most common

21. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Glucose (C 6 H 12 O 6 ) is the most common monosaccharide in living organisms –Sugar dissolving in water Fig. 3-3 hydrogen bond hydroxyl group water

22. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Additional monosaccharides are: –Fructose (“fruit sugar” found in fruits, corn syrup, and honey) –Galactose (“milk sugar” found in lactose) –Ribose and deoxyribose (found in RNA and DNA, respectively)

23. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Monosaccharides Fig. 3-5 galactose fructose 6 5 4 3 2 1 2 3 4 5 1 6

24. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Ribose Sugars Fig. 3-6 ribosedeoxyribose 5 4 32 1 5 4 32 1 Note “missing” oxygen atom

25. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  There are several monosaccharides with slightly different structures (continued) –The fate of monosaccharides inside a cell is: –Some are broken down to free their chemical energy –Some are linked together by dehydration synthesis

26. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Disaccharides consist of two monosaccharides linked by dehydration synthesis –Disaccharides are two-part sugars –They are used for short-term energy storage –When energy is required, they are broken apart into their monosaccharide subunits by hydroysis

27. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Synthesis of a Disaccharide Fig. 3-7 glucosefructose sucrose dehydration synthesis

28. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Examples of disaccharides include: –Sucrose (table sugar) = glucose + fructose –Lactose (milk sugar) = glucose + galactose –Maltose (malt sugar) = glucose + glucose

29. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Polysaccharides are chains of simple sugars –Storage polysaccharides include: –Starch, an energy-storage molecule in plants, formed in roots and seeds –Glycogen, an energy-storage molecule in animals, found in the liver and muscles –Both starch and glycogen are polymers of glucose molecules

30. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Starch is an Energy-Storing Plant Polysaccharide (b) A starch molecule (a) Potato cells (c) Detail of a starch molecule starch grains Fig. 3-8

31. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Polysaccharides are chains of simple sugars (continued) –Many organisms use polysaccharides as a structural material –Cellulose (a polymer of glucose) is one of the most important structural polysaccharides –It is found in the cell walls of plants –It is indigestible for most animals due to the orientation of the bonds between glucose molecules

32. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Carbohydrate Structure and Function

33. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Cellulose Structure and Function Fig. 3-9

34. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.3 What Are Carbohydrates?  Polysaccharides are chains of simple sugars (continued) –Chitin (a polymer of modified glucose units) is found in: –The outer coverings of insects, crabs, and spiders –The cell walls of many fungi

35. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Chitin: A Unique Polysaccharide Fig. 3-10

36. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Lipids are a diverse group of molecules that contain regions composed almost entirely of hydrogen and carbon –All lipids contain large chains of nonpolar hydrocarbons –Most lipids are therefore hydrophobic and water insoluble

37. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Lipids

38. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Lipids are diverse in structure and serve a variety of functions –They are used for energy storage –They form waterproof coverings on plant and animal bodies –They serve as the primary component of cellular membranes –Still others are hormones

39. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Lipids in Nature: Fat Fig. 3-11a

40. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Lipids are classified into three major groups –Oils, fats, and waxes –Phospholipids –Steroids containing rings of carbon, hydrogen, and oxygen

41. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Oils, fats, and waxes –Oils, fats, and waxes are made of one or more fatty acid subunits –Fats and oils –Are used primarily as energy-storage molecules, containing twice as many calories per gram as carbyhydrates and proteins –Are formed by dehydration synthesis –Three fatty acids + glycerol  triglyceride

42. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e glycerolfatty acids triglyceride   Synthesis of a Triglyceride Fig. 3-12

43. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Oils, fats, and waxes (continued) –Fats that are solid at room temperature are saturated (the carbon chain has as many hydrogen atoms as possible, and mostly or all C- C bonds); for example, beef fat

44. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e A Fat Fig. 3-13a

45. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Oils, fats, and waxes (continued) –Fats that are liquid at room temperature are unsaturated (with fewer hydrogen atoms, and many C=C bonds); for example, corn oil –Unsaturated trans fats have been linked to heart disease

46. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Triglycerides

47. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e An Oil Fig. 3-13b

48. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Oils, fats, and waxes (continued) –Waxes are highly saturated and solid at room temperature

49. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Oils, fats, and waxes (continued) –Waxes form waterproof coatings such as on: –Leaves and stems in plants –Fur in mammals –Insect exoskeletons –Waxes are also used to build honeycomb structures

50. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Lipids in Nature: Wax Fig. 3-11b

51. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Phospholipids –These form plasma membranes around all cells –Phospholipids consist of two fatty acids + glycerol + a short polar functional group –They have hydrophobic and hydrophilic portions –The polar functional groups form the “head” and are water-soluble –The nonpolar fatty acids form the “tails” and are water insoluble

52. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Phospholipids

53. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Phospholipids Fig. 3-14 polar head glycerol backbone phosphate group variable functional group (hydrophilic) (hydrophobic) fatty acid tails

54. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.4 What Are Lipids?  Steroids –Steroids are composed of four carbon rings fused together with various functional groups protruding from them –Examples of steroids include: –Cholesterol –Found in the membranes of animal cells –Male and female sex hormones

55. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Steroids

56. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Steroids Fig. 3-15

57. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  Functions of proteins –Proteins have a variety of functions –Enzymes are proteins that promote chemical reactions –Structural proteins (e.g., elastin) provide support

58. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Structural Proteins Fig. 3-16

59. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  Proteins are formed from chains of amino acids joined by peptide bonds –All amino acids have a similar structure –All contain amino and carboxyl groups –All have a variable “R” group –Some R groups are hydrophobic –Some are hydrophilic –Cysteine R groups can form disulfide bridges

60. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Amino Acid Structure Fig. 3-17 amino group hydrogen variable group carboxylic acid group

61. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e glutamic acid (glu)aspartic acid (asp) (a) Hydrophilic functional groups(b) Hydrophobic functional groups (c) Sulfur-containing functional group leucine (leu)phenylalanine (phe) cysteine (cys) Amino Acid Diversity Fig. 3-18

62. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  The sequence of amino acids in a protein dictates its function

63. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  Amino acids are joined to form chains by dehydration synthesis –An amino group reacts with a carboxyl group, and water is lost

64. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Protein Synthesis Fig. 3-19 amino acid amino group amino group carboxylic acid group amino acidpeptide water peptide bond  dehydration synthesis

65. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  Amino acids are joined to form chains by dehydration synthesis (continued) –The covalent bond resulting after the water is lost is a peptide bond, and the resulting chain of two amino acids is called a peptide –Long chains of amino acids are known as polypeptides, or just proteins

66. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  Proteins exhibit up to four levels of structure –Primary structure is the sequence of amino acids linked together in a protein –Secondary structure is a helix, or a pleated sheet –Tertiary structure refers to complex foldings of the protein chain held together by disulfide bridges, hydrophobic/hydrophilic interactions, and other bonds –Quaternary structure occurs where multiple protein chains are linked together

67. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Author Animation: Protein Structure

68. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e The Four Levels of Protein Structure Fig. 3-20 (a) Primary structure: The sequence of amino acids linked by peptide bonds (c) Tertiary structure: Folding of the helix results from hydrogen bonds with surrounding water molecules and disulfide bridges between cysteine amino acids (d) Quaternary structure: Individual polypeptides are linked to one another by hydrogen bonds or disulfide bridges (b) Secondary structure: Usually maintained by hydrogen bonds, which shape this helix helix hydrogen bond heme group leu val lys gly his ala lys val lys pro

69. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e The Pleated Sheet: An Example of Secondary Structure Fig. 3-21 pleated sheet hydrogen bond

70. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.5 What Are Proteins?  The functions of proteins are linked to their three-dimensional structures –Precise positioning of amino acid R groups leads to bonds that determine secondary and tertiary structure –Disruption of secondary and tertiary bonds leads to denatured proteins and loss of function

71. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.6 What Are Nucleic Acids?  Nucleotides act as energy carriers and intracellular messengers –Nucleotides are the monomers of nucleic acid chains –All nucleotides are made of three parts: –Phosphate group –Five-carbon sugar –Nitrogen-containing base

72. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e sugar phosphate base Deoxyribose Nucleotide Fig. 3-22

73. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.6 What Are Nucleic Acids?  Nucleotides act as energy carriers and intracellular messengers (continued) –Adenosine triphosphate (ATP) is a deoxyribose nucleotide with three phosphate functional groups

74. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e The Energy-Carrier Molecule Adenosine Triphosphate (ATP) Fig. 3-23

75. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.6 What Are Nucleic Acids?  DNA and RNA, the molecules of heredity, are nucleic acids –There are two types of polymers of nucleic acids –DNA (deoxyribonucleic acid) is found in chromosomes and carries genetic information needed for protein construction –RNA (ribonucleic acid) makes copies of DNA and is used directly in the synthesis of proteins

76. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e 3.6 What Are Nucleic Acids?  Each DNA molecule consists of two chains of nucleotides that form a double helix linked by hydrogen bonds

77. Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Deoxyribonucleic Acid Fig. 3-24 hydrogen bond