1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 5 The Structure and Function of Macromolecules

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: The Molecules of Life Macromolecules are large molecules composed of thousands of covalently connected atoms

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.1: Most macromolecules are polymers, built from monomers A polymer is a long molecule consisting of many similar building blocks called monomers Three of the four classes of life’s organic molecules are polymers: – Carbohydrates – Proteins – Nucleic acids

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Dehydration reaction in the synthesis of a polymer Longer polymer Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer The Synthesis and Breakdown of Polymers Dehydration synthesis Hydrolysis Animation: Polymers Animation: Polymers

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dehydration Synthesis and Hydrolysis

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.2: Carbohydrates serve as fuel and building material Carbohydrates include sugars and the polymers of sugars – Monosaccharides – Disaccharides – Polysaccharides

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sugars Monosaccharides have molecular formulas that are usually multiples of CH 2 O Glucose is the most common monosaccharide

8. LE 5-3 Triose sugars (C 3 H 6 O 3 ) Glyceraldehyde Aldoses Ketoses Pentose sugars (C 5 H 10 O 5 ) Ribose Hexose sugars (C 5 H 12 O 6 ) Glucose Galactose Dihydroxyacetone Ribulose Fructose

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Linear and ring forms Abbreviated ring structure Monosaccharides serve as a major fuel for cells and as raw material for building molecules – in aqueous solutions they form rings

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A disaccharide is formed when a dehydration reaction joins two monosaccharides – glycosidic linkage Animation: Disaccharides Animation: Disaccharides

11. LE 5-5 Glucose Maltose Fructose Sucrose Glucose Dehydration reaction in the synthesis of maltose Dehydration reaction in the synthesis of sucrose 1–4 glycosidic linkage 1–2 glycosidic linkage

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Polysaccharides Polysaccharides, the polymers of sugars, have storage and structural roles

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ChloroplastStarch 1 µm Amylose Starch: a plant polysaccharide Amylopectin Storage Polysaccharides Starch, a storage polysaccharide of plants, consists entirely of glucose monomers

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycogen is a storage polysaccharide in animals Mitochondria Glycogen granules 0.5 µm Glycogen Glycogen: an animal polysaccharide

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Structural Polysaccharides Cellulose is a major component of the tough wall of plant cells – glycosidic linkages differ from starch The difference is based on two ring forms for glucose: alpha (  ) and beta (  ) Animation: Polysaccharides Animation: Polysaccharides

16. LE 5-7 a Glucose a and b glucose ring structures b Glucose Starch: 1–4 linkage of a glucose monomers. Cellulose: 1–4 linkage of b glucose monomers.

17. LE 5-8 Cellulose molecules Cellulose microfibrils in a plant cell wall Cell walls Microfibril Plant cells 0.5 µm  Glucose monomer

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chitin – exoskeleton of arthropods – cell walls of many fungi Chitin can be used as surgical thread

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.3: Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers – no affinity for water (hydrophobic) Fats Phospholipids Steroids

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fats – constructed from: Glycerol Fatty acids Animation: Fats Animation: Fats

22. LE 5-11a Dehydration reaction in the synthesis of a fat Glycerol Fatty acid (palmitic acid)

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride Ester linkage Fat molecule (triacylglycerol)

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Saturated fatty acids Unsaturated fatty acids

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Saturated fat and fatty acid. Stearic acid Saturated fats – Most animal fats are saturated (except fish) – solid at room temperature – may contribute to cardiovascular disease through plaque deposits

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Unsaturated fats – Plant fats and fish fats – liquid at room temperature and are called oils Unsaturated fat and fatty acid. Oleic acid cis double bond causes bending

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids Phospholipid – two fatty acids and a phosphate group – attached to glycerol Fatty acid tails are hydrophobic Phosphate group are hydrophilic

28. LE 5-13 Structural formula Space-filling model Phospholipid symbol Hydrophilic head Hydrophobic tails Fatty acids Choline Phosphate Glycerol Hydrophobic tails Hydrophilic head

29. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids self-assemble into a bilayer WATER Hydrophilic head Hydrophobic tails WATER

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Steroids Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Cholesterol, an important steroid, is a component in animal cell membranes

31. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.4: Proteins have many structures, resulting in a wide range of functions Proteins account for more than 50% of the dry mass of most cells – Functions include: Structural support Storage Transport Cellular communications Movement Defense against foreign substances

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

33. Animation: Structural Proteins Animation: Structural Proteins Animation: Storage Proteins Animation: Storage Proteins Animation: Transport Proteins Animation: Transport Proteins Animation: Receptor Proteins Animation: Receptor Proteins Animation: Contractile Proteins Animation: Contractile Proteins Animation: Defensive Proteins Animation: Defensive Proteins Animation: Enzymes Animation: Enzymes Animation: Hormonal Proteins Animation: Hormonal Proteins Animation: Sensory Proteins Animation: Sensory Proteins Animation: Gene Regulatory Proteins Animation: Gene Regulatory Proteins

34. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Substrate (sucrose) Enzyme (sucrose) Fructose Glucose Enzymes acts as a catalyst, speeding up chemical reactions Enzymes can perform their functions repeatedly

35. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Amino Acid Monomers Amino acids – differ in their properties due to differing side chains, called R groups Cells use 20 amino acids to make thousands of proteins Amino group Carboxyl group  carbon

36. LE 5-17a Isoleucine (Ile) Methionine (Met) Phenylalanine (Phe) Tryptophan (Trp) Proline (Pro) Leucine (Leu) Valine (Val) Alanine (Ala) Nonpolar Glycine (Gly)

37. LE 5-17b Asparagine (Asn) Glutamine (Gln)Threonine (Thr) Polar Serine (Ser) Cysteine (Cys) Tyrosine (Tyr)

38. LE 5-17c Electrically charged Aspartic acid (Asp) Acidic Basic Glutamic acid (Glu) Lysine (Lys)Arginine (Arg) Histidine (His)

39. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Amino Acid Polymers Amino acids are linked by peptide bonds A polypeptide is a polymer of amino acids

40. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Protein Conformation and Function Functional protein – one or more polypeptides twisted, folded, and coiled into a unique shape – conformation determines function Groove A space-filling model A ribbon model Groove

41. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Four Levels of Protein Structure Primary structure – unique sequence of amino acids Secondary structure – coils and folds in the polypeptide chain (H bonds) Tertiary structure – interactions among various R groups (various bonds) Quaternary structure – protein consists of multiple polypeptide chains Animation: Protein Structure Introduction Animation: Protein Structure Introduction

42. LE 5-20 Amino acid subunits  pleated sheet + H 3 N Amino end  helix

43. LE 5-20a Amino acid subunits Carboxyl end Amino end Animation: Primary Protein Structure Animation: Primary Protein Structure

44. LE 5-20b Amino acid subunits  pleated sheet  helix Animation: Secondary Protein Structure Animation: Secondary Protein Structure

45. LE 5-20d Hydrophobic interactions and van der Waals interactions Polypeptide backbone Disulfide bridge Ionic bond Hydrogen bond Animation: Tertiary Protein Structure Animation: Tertiary Protein Structure

46. LE 5-20e  Chains  Chains Hemoglobin Iron Heme Collagen Polypeptide chain Polypeptide chain Animation: Quaternary Protein Structure Animation: Quaternary Protein Structure

47. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sickle-Cell Disease: A Simple Change in Primary Structure A slight change in primary structure can affect a protein’s conformation and ability to function Sickle-cell disease – results from a single amino acid substitution in the protein hemoglobin Red blood cell shape Normal cells are full of individual hemoglobin molecules, each carrying oxygen. 10 µm Red blood cell shape Fibers of abnormal hemoglobin deform cell into sickle shape.

48. LE 5-21b Primary structure Secondary and tertiary structures 1 2 3 Normal hemoglobin Val His Leu 4 Thr 5 Pro 6 Glu 7 Primary structure Secondary and tertiary structures 1 2 3 Sickle-cell hemoglobin Val His Leu 4 Thr 5 Pro 6 ValGlu 7 Quaternary structure Normal hemoglobin (top view)         Function Molecules do not associate with one another; each carries oxygen. Quaternary structure Sickle-cell hemoglobin Function Molecules interact with one another to crystallize into a fiber; capacity to carry oxygen is greatly reduced. Exposed hydrophobic region  subunit

49. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings What Determines Protein Conformation? In addition to primary structure, physical and chemical conditions can affect conformation Alternations in pH Salt concentration Temperature This loss of a protein’s native conformation is called denaturation

50. LE 5-22 Denaturation Renaturation Denatured proteinNormal protein

51. LE 5-23a Chaperonin (fully assembled) Hollow cylinder Cap Chaperonins are protein molecules that assist the proper folding of other proteins

52. LE 5-23b Polypeptide Correctly folded protein An unfolded poly- peptide enters the cylinder from one end. Steps of Chaperonin Action: The cap comes off, and the properly folded protein is released. The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide.

53. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.5: Nucleic acids store and transmit hereditary information The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene Genes are made of DNA, a nucleic acid

54. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Roles of Nucleic Acids There are two types of nucleic acids: – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) DNA directs: – its own replication – synthesis of messenger RNA (mRNA)

55. LE 5-25 NUCLEUS DNA CYTOPLASM mRNA Ribosome Amino acids Synthesis of mRNA in the nucleus Movement of mRNA into cytoplasm via nuclear pore Synthesis of protein Polypeptide

56. LE 5-26a 5 end 3 end Nucleoside Nitrogenous base Phosphate group Nucleotide Polynucleotide, or nucleic acid Pentose sugar Nucleic acids are polymers called polynucleotides

57. LE 5-26b Nitrogenous bases Pyrimidines Purines Pentose sugars Cytosine C Thymine (in DNA) T Uracil (in RNA) U Adenine A Guanine G Deoxyribose (in DNA) Nucleoside components Ribose (in RNA) There are two families of nitrogenous bases: Pyrimidines have a single six-membered ring Purines have a six- membered ring fused to a five-membered ring

58. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The DNA Double Helix DNA double helix: – two backbones run in opposite 5´ to 3´ directions an arrangement referred to as antiparallel One DNA molecule includes many genes

59. LE 5-27 Sugar-phosphate backbone 3 end 5 end Base pair (joined by hydrogen bonding) Old strands Nucleotide about to be added to a new strand 5 end New strands 3 end 5 end 3 end 5 end

60. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings DNA and Proteins as Tape Measures of Evolution The linear sequences of nucleotides in DNA molecules are passed from parents to offspring Two closely related species are more similar in DNA than are more distantly related species – Molecular biology can be used to assess evolutionary kinship