1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 5 The Structure and Function of Large Biological Molecules Macromolecules - large molecules composed of thousands of covalently connected atoms Molecular structure and function are inseparable

2. Concept 5.1: Macromolecules are polymers, built from monomers Polymer - long molecule consisting of many similar building blocks – Small building-block molecules = monomers Three of the four classes of life’s organic molecules are polymers: – Carbohydrates – Proteins – Nucleic acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3. Condensation reaction (aka dehydration reaction) - two monomers bond together through the loss of a water molecule – Enzymes - macromolecules that speed up the dehydration process Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction The Synthesis and Breakdown of Polymers Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

4. Fig. 5-2a Dehydration removes a water molecule, forming a new bond Short polymerUnlinked monomer Longer polymer Dehydration reaction in the synthesis of a polymer HO H2OH2O H H H 4 3 2 1 1 2 3 (a)

5. Fig. 5-2b Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer HO H2OH2O H H H 3 2 1 1 23 4 (b)

6. Concept 5.2: Carbohydrates serve as fuel and building material Carbohydrates include sugars and the polymers of sugars – simplest = monosaccharides (AKA single sugars) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7. Sugars Monosaccharides - molecular formula usually multiples of CH 2 O – Glucose (C 6 H 12 O 6 ) - most common monosaccharide Monosaccharides are classified by – The location of the carbonyl group (as aldose or ketose) – The number of carbons in the carbon skeleton – Though often drawn as linear skeletons, in aqueous solutions many sugars form rings – Fxn. fuel for cells and as raw material for building molecules Disaccharide - two monosaccharides joined with a covalent bond called a glycosidic linkage Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

8. Fig. 5-3 Dihydroxyacetone Ribulose Ketoses Aldoses Fructose Glyceraldehyde Ribose Glucose Galactose Hexoses (C 6 H 12 O 6 ) Pentoses (C 5 H 10 O 5 ) Trioses (C 3 H 6 O 3 )

9. Fig. 5-4 (a) Linear and ring forms(b) Abbreviated ring structure

10. Polysaccharides Polysaccharides - polymers of sugars, have storage and structural roles – structure and function are determined by its sugar monomers and the positions of glycosidic linkages Starch - storage (plants), consists entirely of glucose monomers. Plants store surplus starch as granules within chloroplasts and other plastids Glycogen - storage (animals) Humans and other vertebrates store glycogen mainly in liver and muscle cells. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

11. Fig. 5-6 (b) Glycogen: an animal polysaccharide Starch Glycogen Amylose Chloroplast (a) Starch: a plant polysaccharide Amylopectin Mitochondria Glycogen granules 0.5 µm 1 µm

12.  Glucose monomer Cellulose molecules Microfibril Cellulose microfibrils in a plant cell wall 0.5 µm 10 µm Cell walls Cellulose – found in cell walls of plant polymer of glucose, but the glycosidic linkages differ

13. Enzymes that digest starch by hydrolyzing  linkages can’t hydrolyze  linkages in cellulose Cellulose in human food passes through the digestive tract as insoluble fiber Some microbes use enzymes to digest cellulose Many herbivores, from cows to termites, have symbiotic relationships with these microbes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

14. Fig. 5-10 The structure of the chitin monomer. (a) (b) (c) Chitin forms the exoskeleton of arthropods. Chitin is used to make a strong and flexible surgical thread. Chitin - found in the exoskeleton of arthropods structural support for the cell walls of many fungi

15. Concept 5.3: Lipids are a diverse group of hydrophobic molecules Lipids – do not form polymers – Have little or no affinity for water – hydrophobic because  of hydrocarbons, which form nonpolar covalent bonds E.g. fats, phospholipids, and steroids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

16. Fig. 5-11 Fatty acid (palmitic acid) Glycerol (a) Dehydration reaction in the synthesis of a fat Ester linkage (b) Fat molecule (triacylglycerol) Fats = glycerol + fatty acids Glycerol - three-carbon alcohol with a hydroxyl group attached to each carbon Fatty acid - carboxyl group attached to a long carbon skeleton

17. Fig. 5-12 Structural formula of a saturated fat molecule Stearic acid, a saturated fatty acid (a) Saturated fat Structural formula of an unsaturated fat molecule Oleic acid, an unsaturated fatty acid (b) Unsaturated fat cis double bond causes bending In a fat, three fatty acids are joined to glycerol by an ester linkage - triglyceride Saturated fatty acids – maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids - have one or more double bonds Saturated fatty acids - solid at room temperature; most animal fats are saturated; may contribute to cardio-vascular disease through plaque deposits Unsaturated fatty acids - liquid at room temperature; eg. Plant and fish

18. Hydrogenation -process of converting unsaturated fats to saturated fats by adding hydrogen – creates unsaturated fats with trans double bonds – trans fats may contribute more than saturated fats to cardiovascular disease The major function of fats is energy storage – Humans and other mammals store their fat in adipose cells – Adipose tissue also cushions vital organs and insulates the body Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

19. Fig. 5-13 (b) Space-filling model (a)(c) Structural formula Phospholipid symbol Fatty acids Hydrophilic head Hydrophobic tails Choline Phosphate Glycerol Hydrophobic tails Hydrophilic head Phospholipid - two fatty acids and a phosphate group are attached to glycerol Major component of all cell membranes

20. Fig. 5-14 Hydrophilic head Hydrophobic tail WATER

21. Steroids Steroids - lipids characterized by a carbon skeleton consisting of four fused rings – E.g. Cholesterol - component in animal cell membranes – Although essential in animals, high levels may contribute to cardiovascular disease Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

22. Table 5-1 Proteins account for more than 50% of the dry mass of most cells Enzymes - type of protein that acts as a catalyst to speed up chemical reactions

23. Fig. 5-16 Enzyme (sucrase) Substrate (sucrose) Fructose Glucose OH H O H2OH2O

24. Polypeptides Polypeptides - polymers built from the same set of 20 amino acids Protein - one or more polypeptides Amino acids - organic molecules with carboxyl and amino groups – Amino acids differ in their properties due to differing side chains, called R groups Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

25. Fig. 5-UN1 Amino group Carboxyl group  carbon

26. Fig. 5-17a Nonpolar Glycine (Gly or G) Alanine (Ala or A) Valine (Val or V) Leucine (Leu or L) Isoleucine (Ile or I) Methionine (Met or M) Phenylalanine (Phe or F) Tryptophan (Trp or W) Proline (Pro or P)

27. Fig. 5-17b Polar Asparagine (Asn or N) Glutamine (Gln or Q) Serine (Ser or S) Threonine (Thr or T) Cysteine (Cys or C) Tyrosine (Tyr or Y)

28. Fig. 5-17c Acidic Arginine (Arg or R) Histidine (His or H) Aspartic acid (Asp or D) Glutamic acid (Glu or E) Lysine (Lys or K) Basic Electrically charged

29. Peptide bond Fig. 5-18 Amino end (N-terminus) Peptide bond Side chains Backbone Carboxyl end (C-terminus) (a) (b) Amino acids are linked by peptide bonds A polypeptide is a polymer of amino acids

30. Fig. 5-19 A ribbon model of lysozyme (a)(b) A space-filling model of lysozyme Groove A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape The sequence of amino acids determines a protein’s three- dimensional structure A protein’s structure determines its function

31. Fig. 5-20 Antibody protein Protein from flu virus

32. Amino acid subunits + H 3 N Amino end 25 20 15 10 5 1 Primary Structure Primary structure - sequence of amino acids and determined by inherited genetic information Four Levels of Protein Structure

33. Secondary Structure  pleated sheet Examples of amino acid subunits  helix Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain connected by hydrogen bonds

34. Fig. 5-21d Abdominal glands of the spider secrete silk fibers made of a structural protein containing  pleated sheets. The radiating strands, made of dry silk fibers, maintain the shape of the web. The spiral strands (capture strands) are elastic, stretching in response to wind, rain, and the touch of insects.

35. Fig. 5-21f Polypeptide backbone Hydrophobic interactions and van der Waals interactions Disulfide bridge Ionic bond Hydrogen bond Tertiary structure - determined by interactions between R groups

36. Tertiary StructureQuaternary Structure Quaternary structure results when a protein consists of multiple polypeptide chains

37. Fig. 5-21g Polypeptide chain  Chains Heme Iron  Chains Collagen Hemoglobin Collagen -a fibrous protein consisting of three polypeptides coiled like a rope Hemoglobin -globular protein consisting of four polypeptides: two alpha and two beta chains

38. Primary structure Secondary and tertiary structures Quaternary structure Normal hemoglobin (top view) Primary structure Secondary and tertiary structures Quaternary structure Function  subunit Molecules do not associate with one another; each carries oxygen. Red blood cell shape Normal red blood cells are full of individual hemoglobin moledules, each carrying oxygen. 10 µm Normal hemoglobin     1234567 Val His Leu ThrPro Glu Red blood cell shape  subunit Exposed hydrophobic region Sickle-cell hemoglobin   Molecules interact with one another and crystallize into a fiber; capacity to carry oxygen is greatly reduced.   Fibers of abnormal hemoglobin deform red blood cell into sickle shape. 10 µm Sickle-cell hemoglobin GluPro Thr Leu His Val 1234567 A slight change in 1 0 structure can affect a protein’s structure and ability to function

39. Normal protein Denatured protein Denaturation Renaturation Denaturation - loss of a protein’s native structure (biologically inactive) Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel

40. Fig. 5-24 Hollow cylinder Cap Chaperonin (fully assembled) Polypeptide Steps of Chaperonin Action: An unfolded poly- peptide enters the cylinder from one end. 1 23 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. The cap comes off, and the properly folded protein is released. Correctly folded protein Chaperonins - protein molecules that assist the proper folding of other proteins

41. Nucleic acids store and transmit hereditary info 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 There are two types of nucleic acids: – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) DNA provides directions for its own replication DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis Protein synthesis occurs in ribosomes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

42. Fig. 5-26-3 mRNA Synthesis of mRNA in the nucleus DNA NUCLEUS mRNA CYTOPLASM Movement of mRNA into cytoplasm via nuclear pore Ribosome Amino acids Polypeptide Synthesis of protein 1 2 3

43. Fig. 5-27 5 end Nucleoside Nitrogenous base Phosphate group Sugar (pentose) (b) Nucleotide (a) Polynucleotide, or nucleic acid 3 end 3C3C 3C3C 5C5C 5C5C Nitrogenous bases Pyrimidines Cytosine (C) Thymine (T, in DNA)Uracil (U, in RNA) Purines Adenine (A)Guanine (G) Sugars Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components: sugars Nucleotide (monomers) = nitrogenous base, a pentose sugar, & a phosphate group Nucleoside - nucleotide without the phosphate

44. Nucleotide Monomers There are two families of nitrogenous bases: – Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring – Purines (adenine and guanine) have a six- membered ring fused to a five-membered ring In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose Sugar-phosphate units create a backbone with nitrogenous bases as appendages Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

45. Sugar-phosphate backbones 3' end 5' end Base pair (joined by hydrogen bonding) Old strands New strands Nucleotide about to be added to a new strand Double helix - shape In the DNA double helix, the two backbones run in opposite 5 → 3 directions from each other, an arrangement referred to as antiparallel Nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) with thymine (T), and guanine (G) with cytosine (C)

46. 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 Higher levels of organization result in the emergence of new properties. Organization is the key to the chemistry of life. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings