1. Chapter 5 The Structure and Function of Macromolecules

2. Introduction cells join smaller organic molecules together to form larger molecules the four main classes of macromolecules are: carbohydrates,lipids,proteins, and nucleic acids

3. Large molecules formed by joining many subunits together Macromolecules also known as “polymers”

4. Monomer a building block of a polymer repeated linked units

5. Condensation Synthesis or Dehydration Synthesis the chemical reaction that joins monomers into polymers covalent bonds are formed by the removal of a water molecule between the monomers

6. one monomer provides the hydroxyl group and the other provides a hydrogen together these form water

7. Hydrolysis the reverse of condensation synthesis (dehydration synthesis) Hydro = waterLysis = to split the covalent bonds connecting monomers in a polymer are disassembled by hydrolysis

8. in hydrolysis, as the covalent bond is broken a hydrogen atom and hydroxyl group from a split water molecule attaches where the covalent bond used to be

9. hydrolysis will break polymers into monomers by adding water hydrolysis reactions dominate the digestive process, guided by specific enzymes

10. An immense variety of polymers can be built from a small set of monomers each cell has thousands of different macromolecules these monomers can be connected in various combinations, like the 26 letters in the alphabet can be used to create a great diversity of words

11. Four Main Types of Macromolecules carbohydrates lipids proteins nucleic acids

12. Carbohydrates include both sugars and the polymers of sugars used for fuel, building materials, and receptors made of C, H, O general formula is CH 2 O most names for sugars end in -ose

13. Types of Carbohydrates 1. monosaccharides 2. disaccharides 3. polysaccharides

14. Monosaccharides mono = single (one) saccharide = sugar simplest of all carbohydrates 3 to 7 carbons

15. monosaccharides are also classified by the number of carbons in the backbone can be in linear or ring forms

17. Disaccharides two monosaccharides can join with a glycosidic linkage to form a disaccharide via dehydration

18. maltose, malt sugar, is formed by joining two glucose molecules sucrose, table sugar, is formed by joining glucose and fructose and is the major transport form of sugars in plants

19. Polysaccharides the polymers of sugars, have storage and structural roles many joined simple sugars (can be hundreds to thousands of monosaccharides joined by glycosidic linkages)

20. one function of polysaccharides is as an energy storage macromolecule that is hydrolyzed as needed

21. other polysaccharides serve as building materials for the cell or whole organisms

22. Starch a storage polysaccharide composed entirely of glucose monomers made of 1 - 4 linkages of α glucose linkage makes the molecule form a helix

23. fuel storage in plants α glucoseβ glucose

24. Cellulose made of 1 – 4 β glucose linkage makes the molecule form a straight line used for structure in plant cell walls

26. most organisms can digest starch (1 – 4 α linkage), but very few can digest cellulose (1 – 4 β linkage)

27. Glycogen “animal starch” similar to starch, but has more 1 - 6 linkages or branches

28. humans and other vertebrates store glycogen in the liver and muscles but only have about a one- day supply

29. Chitin another structural polysaccharide found in the exoskeletons of arthropods and cell walls of many fungi

30. similar to cellulose, except that it has a nitrogen-containing appendage on each glucose monomer

31. Lipids The unifying feature of lipids is that they all have little or no affinity for water this is because their structure are dominated by nonpolar covalent bonds

32. lipids are diverse hydrophobic molecules made of C, H, O lipids store large amounts of energy unlike other macromolecules, lipids do not form polymers

33. Fats and Oils Fats – solid at room temperature Oils – liquid at room temperature

34. Fats and Oils Made of two kinds of smaller molecules 1. glycerol 2. fatty acids

35. Fatty Acids A long carbon chain (12 – 18 carbons) with a –COOH (acid) on one end and a –CH 3 (fat) at the other

36. Triglycerides (Triacylglycerols) three fatty acids joined to one glycerol

37. joined by an ester linkage between the –COOH of the fatty acid and the –OH of the alcohol

38. Saturated Fats saturated – no double bonds most animal fats

39. Unsaturated Fats unsaturated – one or more C=C bonds double bonds cause “kinks” in the molecule’s shape (can accept more hydrogen)

40. Why do fats usually contain saturated fatty acids and oils usually contain unsaturated fatty acids? The double bond pushes the molecules apart, lowering the density, which lowers the melting point

41. Fats differ in which fatty acids are used used for energy reserve (adipose tissue), cushion for vital organs, insulation

42. Which has more energy, a kg of fat or a kg of starch? Fat – there are more C – H bonds which provide more energy per mass (2x as much energy) (2x as many calories)

43. Phospholipids similar to fats, but have only two fatty acids the third –OH of glycerol is joined to a phosphate containing molecule are major components of cell membranes (arranged as a bilayer)

44. Phospholipids have a hydrophobic tail, but a hydrophilic head

45. The hydrophilic heads are on the outside in contact with the aqueous solution and the hydrophobic tails form the core

46. the phospholipid bilayer forms a barrier between the cell and the external environmental

47. Steroids lipids with four fused rings differ in the functional groups attached to the rings

48. cholesterol – a component in animal cell membranes Examples of Steroids: sex hormones – estrogen and testosterone

49. Proteins made of C, H, O, N, and sometimes S proteins are the most structurally complex molecules known each type of protein has a complex 3-D shape or conformation

50. Uses of Proteins structure enzymes antibodies transport movement receptors hormones

51. Proteins all protein polymers are constructed from the same set of 20 monomers – amino acids polymers of proteins are called polypeptides polypeptide chains of amino acids linked by peptide bonds

52. a protein consists of one or more polypeptides folded and coiled into a specific conformation

53. Amino Acids All have a carbon with four attachments: - COOH (acid) - NH 2 (amine) - H - R (some other side group)

54. R Groups 20 different kinds:

56. The properties of the R groups determine the properties of the protein

57. Polypeptide Chains Amino acids are joined together when a dehydration reaction removes a hydroxyl group from the carboxyl end of one amino acid and a hydrogen from the amino group of another the resulting covalent bond is called a peptide bond

58. (N-C-C) is the polypeptide backbone

59. Levels of Protein Structure Organizing the polypeptide into its 3-D functional shape primary secondary tertiary quaternary

60. Primary sequence of amino acids in the polypeptide chain many different sequences are possible with 20 amino acids

61. Secondary 3-D structure formed by hydrogen bonding between the R groups two main secondary structures: α helix pleated sheets

62. secondary structure of a protein results from hydrogen bonding at regular intervals along the polypeptide backbone

63. Tertiary bonding between R groups Examples: Hydrogen bonds among polar and/or charged areas Ionic bonds between charged R groups

64. Hydrophobic interactions and van der Waals interactions among hydrophobic R groups

65. while these bonds are relatively weak, disulfide bridges, strong covalent bonds that form between the sulfhydryl groups, stabilize the structure

66. Quaternary when two or more polypeptides unite to form a functional protein Example: hemoglobin

67. Is Protein Structure Important?

68. Denaturing of a Protein events that cause a protein to lose structure (and function) Examples: pH shifts high salt concentrations heat

69. These forces disrupt the hydrogen bonds, ionic bonds, and disulfide bridges that maintain the protein’s shape

70. some proteins can return to their functional shape after denaturation, but others cannot, especially in the crowded environment of the cell

71. Nucleic Acids informational polymers made of C, H, O, N, and P Examples: DNA and RNA polymers of nucleotides

72. DNA provides direction for its own replication DNA also directs RNA synthesis and, through RNA, controls protein synthesis

73. Nucleotides Three parts to a nucleotide: 1. nitrogenous base 2. pentose sugar 3. phosphate group

74. Nitrogenous Bases rings of C and N the N atoms tend to take up H + (base)

75. Two types: 1. Pyrimidines (single ring) Cytosine (C), Thymine (T), and Uracil (U)

76. 2. Purines (double rings) Adenine (A) and Guanine (G)

77. Pentose Sugar 5 – C sugar ribose – RNA deoxyribose - DNA RNA and DNA differ in an – OH group on the 2 nd carbon

78. polynucleotides are synthesized by connecting the sugars of one nucleotide to the phosphate of the next with a phosphodiester link

79. this creates a repeating backbone of sugar- phosphate units with the nitrogen bases as appendages

80. A always pairs with T and G always pairs with C