1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chapter 5 The Structure and Function of Macromolecules

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Macromolecules Are large molecules composed of smaller molecules Are complex in their structures Figure 5.1

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.1: Most macromolecules are polymers, built from monomers Three of the classes of life’s organic molecules are polymers

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Diversity of Polymers Each class of polymer – Is formed from a specific set of monomers 1 2 3 HOH

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.2: Carbohydrates Carbohydrates serve as fuel and building material Carbohydrates – Include both monomers and their polymers

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sugars Monosaccharides – Are the simplest sugars – Can be used for fuel – Can be converted into other organic molecules – Can be combined into polymers

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Examples of monosaccharides Triose sugars (C 3 H 6 O 3 ) Pentose sugars (C 5 H 10 O 5 ) Hexose sugars (C 6 H 12 O 6 ) H C OH HO C H H C OH HO C H H C OH C O H C OH HO C H H C OH C O H H H HHH H H HHH H H H C CCC O O O O Aldoses Glyceraldehyde Ribose Glucose Galactose Dihydroxyacetone Ribulose Ketoses Fructose Figure 5.3

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Disaccharides Consist of two monosaccharides Dehydration reaction in the synthesis of maltose. The bonding of two glucose units forms maltose. The glycosidic link joins the number 1 carbon of one glucose to the number 4 carbon of the second glucose. Joining the glucose monomers in a different way would result in a different disaccharide. Dehydration reaction in the synthesis of sucrose. Sucrose is a disaccharide formed from glucose and fructose. Notice that fructose, though a hexose like glucose, forms a five-sided ring. (a) (b) H HO H H OH H OH O H CH 2 OH H HO H H OH H OH O H CH 2 OH H O H H OH H OH O H CH 2 OH H H2OH2O H2OH2O H H O H HO H OH O H CH 2 OH HO OH H CH 2 OH H OH H H HO OH H CH 2 OH H OH H O O H OH H CH 2 OH H OH H O H OH CH 2 OH H HO O CH 2 OH H H OH O O 1 2 1 4 1– 4 glycosidic linkage 1–2 glycosidic linkage Glucose Fructose Maltose Sucrose OH H H Figure 5.5

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Polysaccharides – Are polymers of sugars – Serve many roles in organisms

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Storage Polysaccharides Starch – Is a polymer consisting entirely of glucose monomers

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Starch – Is the major storage form of glucose in plants Chloroplast Starch Amylose Amylopectin 1  m (a) Starch: a plant polysaccharide Figure 5.6

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycogen Consists of glucose monomers Is the major storage form of glucose in animals Mitochondria Giycogen granules 0.5  m (b) Glycogen: an animal polysaccharide Glycogen Figure 5.6

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Structural Polysaccharides Cellulose – Is also a polymer of glucose

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellulose – Has different glycosidic linkages than starch (c) Cellulose: 1– 4 linkage of  glucose monomers H O O CH 2 O H H OH H H H H HO 4 C C C C C C H H H OH H H O CH 2 O H H H H OH H H HO 4 OH CH 2 O H O OH HO 4 1 O CH 2 O H O OH O CH 2 O H O OH CH 2 O H O OH O O CH 2 O H O OH HO 4 O 1 OH O O CH 2 O H O OH O O (a)  and  glucose ring structures (b) Starch: 1– 4 linkage of  glucose monomers 1  glucose  glucose CH 2 O H 1 4 4 1 1 Figure 5.7 A–C

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellulose Plant cells 0.5  m Cell walls Cellulose microfibrils in a plant cell wall  Microfibril CH 2 OH OH OHOH O O O CH 2 OH O O OH O CH 2 OH OH O O CH 2 OH O O OHOH O O OHOH O O OH CH 2 OHOH O O CH 2 OH OH O CH 2 OH O O OHCH 2 OH OH  Glucose monomer O O O O O O Parallel cellulose molecules are held together by hydrogen bonds between hydroxyl groups attached to carbon atoms 3 and 6. About 80 cellulose molecules associate to form a microfibril, the main architectural unit of the plant cell wall. A cellulose molecule is an unbranched  glucose polymer. OH O O Cellulose molecules Figure 5.8 – Is a major component of the tough walls that enclose plant cells

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellulose is difficult to digest Cows have microbes in their stomachs to facilitate this process Figure 5.9

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chitin, another important structural polysaccharide Is found in the exoskeleton of arthropods Can be used as surgical thread (a) The structure of the chitin monomer. O CH 2 O H OH H H H NH C CH 3 O H H (b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emerging in adult form. (c) Chitin is used to make a strong and flexible surgical thread that decomposes after the wound or incision heals. OH Figure 5.10 A–C

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.3: Lipids Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not consist of polymers

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fats – Are constructed from two types of smaller molecules, a single and usually three (b) Fat molecule (triacylglycerol) H H H H H H H H H H H H H H H H O Figure 5.11

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fatty acids Vary in length, and number and locations of they contain

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Saturated fatty acids Have the maximum number of hydrogen atoms possible Have no double bonds (a) Saturated fat and fatty acid Stearic acid Figure 5.12

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Have one or more double bonds (b) Unsaturated fat and fatty acid cis double bond causes bending Oleic acid Figure 5.12 Unsaturated fatty acids - Trans fats are unsaturated fats that have been chemically altered. They have properties of both saturated and unsaturated fats.Trans fats

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids – Have only two fatty acids – Have a instead of a third fatty acid

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipid structure Consists of a hydrophilic “head” and hydrophobic “tails” CH 2 O P O O O CH CH 2 OO C O C O Phosphate Glycerol (a) Structural formula (b) Space-filling model Fatty acids (c) Phospholipid symbol Hydrophobic tails Hydrophilic head Hydrophobic tails – Hydrophilic head CH 2 Choline + Figure 5.13 N(CH 3 ) 3

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The structure of phospholipids Results in a found in cell membranes Hydrophilic head WATER Hydrophobic tail Figure 5.14

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Steroids Are lipids characterized by a carbon skeleton consisting of four fused rings HO CH 3 H3CH3C Figure 5.15 - Found in cell membranes - Is a precursor for some hormones

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.4: Proteins Proteins have many structures, resulting in a wide range of functions inside the cell. Table 5.1

28. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Enzymes Are a type of protein that acts as a speeding up chemical reactions Substrate (sucrose) Enzyme (sucrase) Glucose OH H O H2OH2O Fructose 3 Substrate is converted to products. 1 Active site is available for a molecule of substrate, the reactant on which the enzyme acts. Substrate binds to enzyme. 22 4 Products are released. Figure 5.16

29. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Polypeptides – Are polymers of A protein – Consists of one or more polypeptides

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Amino Acid Monomers Amino acids – Are organic molecules possessing both and – Differ in their properties due to differing side chains, called R groups

31. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 20 different amino acids make up proteins O O–O– H H3N+H3N+ C C O O–O– H CH 3 H3N+H3N+ C H C O O–O– C C O O–O– H H3N+H3N+ CH CH 3 CH 2 C H H3N+H3N+ CH 3 CH 2 CH C H H3N+H3N+ C CH 3 CH 2 C H3N+H3N+ H C O O–O– C H3N+H3N+ H C O O–O– NH H C O O–O– H3N+H3N+ C CH 2 H2CH2C H2NH2N C H C Nonpolar Glycine (Gly) Alanine (Ala) Valine (Val)Leucine (Leu)Isoleucine (Ile) Methionine (Met) Phenylalanine (Phe) C O O–O– Tryptophan (Trp) Proline (Pro) H3CH3C Figure 5.17 S O O–O–

32. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

33. Protein Conformation and Function A protein’s specific conformation – Determines how it functions

34. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Four Levels of Protein Structure is the unique sequence of amino acids in a polypeptide is the folding or coiling of the polypeptide into a repeating configuration is the overall three- dimensional shape of a polypeptide is the overall protein structure that results from the aggregation of two or more polypeptide subunits

35. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Protein showing secondary and tertiary structure Figure 7.8 N-terminus C-terminus  Helix CYTOPLASMIC SIDE

36. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Protein Structure What forces participate in forming a protein’s specific structure? – Hydrogen bonds – Ionic bonds – Disulfide bridges – Hydrophobic interactions

37. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sickle-Cell Disease: A Simple Change in Primary Structure Sickle-cell disease – Results from a single amino acid substitution in the protein hemoglobin

38. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.5: Nucleic acids Store and transmit hereditary information Genes – Are the units of inheritance – for the amino acid sequence of polypeptides – Are made of nucleic acids

39. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Roles of Nucleic Acids There are two types of nucleic acids – (Deoxyribonucleic acid) – (Ribonucleic acid)

40. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Structure of Nucleic Acids Nucleic acids – Exist as polymers called polynucleotides (a) Polynucleotide, or nucleic acid 3’C 5’ end 5’C 3’C 5’C 3’ end OH Figure 5.26 O O O O

41. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Each polynucleotide Consists of monomers called nucleotides Nitrogenous base Nucleoside O O OO OO P CH 2 5’C 3’C Phosphate group Pentose sugar (b) Nucleotide Figure 5.26 O

42. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The sequence of bases along a nucleotide polymer – Is unique for each gene – There are 4 different bases

43. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The DNA Double Helix Cellular DNA molecules – Have two polynucleotides that spiral around an imaginary axis – Form a

44. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The DNA double helix Consists of two nucleotide strands 3’ end Sugar-phosphate backbone Base pair (joined by hydrogen bonding) Old strands Nucleotide about to be added to a new strand A 3’ end 5’ end New strands 3’ end 5’ end Figure 5.27

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The nitrogenous bases in DNA Form hydrogen bonds in a fashion (A with T only, and C with G only)