327216_2009_06_sp (2)

327216_2009_06_sp (2) - UNIVERSITY OF THE WESTERN CAPE...

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Unformatted text preview: UNIVERSITY OF THE WESTERN CAPE REEVALUATION / SI’ECIAL EXAMINATION MAY / JUNE 2009 MODULE NAME : BIOTECHNOLOGY 216 (BIOMOLECULES) MODULE CODE : 327216 DURATION : SHRS MARKS 150 Read the instructions carefully There are THREE sections Answer ail questions in Section A using the form provided. Answer all questions in Section Band C using the exam books provided. SECTION A: 1. (30X2=6{} MARKS) The structural integrity of supramoiecular complexes (assemblies) of multiple components are bonded to each other by all of the following forces EXCEPT: a. covalent bonds b. hydrogen bonds 0. hydrophobic interactions (1. ionic interactions The hydrolysis of a phosphate from which of the following molecules is most thermodynamically favorable? a. ADP b. glucose phosphate c. phosphoenolpyruvate d. adenosine—5'—triphosphate The amino acid with a side—chain pKa near neutrality and which therefore plays an important role as proton donor and acceptor in many enzyme catalyzed reactions lS'. a. histidine. ‘13. cysteine. c. proline. d. serine. 4. Fibrous proteins, such as collagen= have which one of the following properties? a. Highly soluble in water. b. Their hydrophilic residues are directed into the interior of the protein. 0. Exhibit enzymatic activity. d. Serve structural roles in the cell. 5. m is specific in hydrolyzing only peptide bonds in which the carboxyi function is contributed by an arginine or a lysine residue. a. Chymotrypsin b. Carboxypeptidase c. Trypsin d. CNBr 6. Carbohydrate characteristic chemical features include all EXCEPT: a. the potential to form multiple hydrogen bonds. b. the existence of one or more asymmetric centers. c. the ability to exist in either linear or ring structures. d. all are true. ' 7. A glycosidic bond would be present in: a. fi—D—galactosamine. b. methyl~fi~D~giucoside c. 2—deoxywa-D—ribose. d. B—D—glucosewo—phosphate. 8. Cellulose is a: a. (1 —>4)~or-D—inannopyranan. b. (l -34)—[3—D—glucopyranan. c. (l —>6)—0th-glucopyranan. d. (l w6)«ot—D-mannopyranan. 9. Mucopolysaccharides such as form protective coats on animal celis. a. chitin b. ceilulose c. glycogen d. hyaluronic acids 10. Individuals with uncontrolled diabetes mellitus may have ievels of blood __ so they test their blood for 13. 14. 15. 9.05793 elevated; fructose; gluconic acid depressed; glucose; oxidizing sugars elevated; glucose; fructose elevated; glucose; reducing sugars ll. Glycerolphosphoiipids are all EXCEPT: none 12. Certain phospholipids, including also called sphingolipids. essential components of cell membranes. made up of 1,2wdiacylglycerol and a phosphate group. members of the phospholipids. and , participate in complex cellular signaling events. a. b. c. d. phosphatidylcholine; phosphatidylserine phosphatidylserine; phosphatidylalanine phosphatidylcholine; phosphatidylglycerol phosphatidylinositol; phosphatidylcholine All of the following are properties of a coenzynie EXCEPT: a. see-.09“ They are usually actively involved in the catalytic reaction of the enzyme. They tend to be stable to heat. They can serve as intermediate carriers of functional groups. They are protein components. They may contain vitamins as part of their structure. All of the following are true statements about the transition state of a reaction EXCEPT: a. The transition state is not an appropriate indication of the rate of a reaction. The transition state is located at the height ofa free energy diagram. The energy required to raise the average energy of one mole of reactant to the transition state is the free energy of activation. Reaching the transition state indicates that there is a high probability that the reaction will occur. The transition state energy level is the sum of the energy levels of the reactants and products. Characteristics of glycogen phosphorylase include all EXCEPT: a b. c. d. e. covalently linked pyridoxal phosphate. an active site at the center of each of two identical subunits. regulatory phosphorylation site on a Ser residue. allosteric effector sites for ATP and glucose-é—phosphate. all are true. 16. In stage 2 of aerobic catabolism of lipids the carbons appear as: a. py ruvate . b. (3024 . c. acetyl group of acetyl—CoA. d. glucose. 6. alanine. l7. _fl __ uses seven of the same enzymes as glycolysis, but must replace three enzymes of glycolysis because they are a. Catabolism; to oxidative M— b. Gluconeogenesis; irreversible c. Oxidative phosphoryiation; reductive d. Gluconeogenesis; anabolic e. Oxidative pliosphorylation; irreversibie 18. In the case of shared anabolic and cat the points of regulation. 3. largest enzymes b. ATP producing enzymes c. NADH utilizing enzymes d. e. abolic pathways, the _ serve as mean-“WM rate—limiting enzymes all are true 19. The function of NADPH is to: provide reducing equivalents to synthesize glucose from C02. carry electrons from anabolic reactions. provide a source of hydrogens for oxidative biosynthesis. be reduced by hydride ions to form NADi. ' produce an oxidative product. a. b. c. d. C. 20. All are characteristics of coenzyrnes EXCEPT: a. carry functional groups. b. maintenance of original structure. 0. provide a broader range of catalytic properties. (:1. can be derived from waterusoluble vitamins. e. can serve as an electron carrier. 21. Hexokinase and glucokinase belong to the kinase subciass of what class of enzymes? a. oxidoreductase b. isomerase c. transferase d. hydrolase e. lyase 22. in the TCA cycle, carbon enters the cycie as M with metabolic energy captured as mm. a. malonate; water; NADH; ATP; NADPH and exits as acetyi~CoA; C02; NADH; ATP; NADPH succinyi-COA; C02; ATP; NADH; NADPH acetyi—COA; C02; ATP; NADH; {FADHfl malonyI—COA; water; NADH; [FADHg]; ATP 09.093" 23. The _ of pyruvate to acetyE—COA is cataiyzed by dehydration; pyruvate dehydration complex oxidative decar‘ooxylations; pyruvate dehydrogenase complex decarboxylations; pyruvate decarboxylase transacylation; pyruvate transacylase none of the above. trance 24. Inhibition of the citric acid cycie at isocitrate dehydrogenase increases the ievels of citrate and isocitrate that may increase the production of: a. amino acids. '9. pyruvate and oxaioacctate. c. giyoxylate and cytosolic acetyi—CoA. d. succinate and fumarate. e. lactate and alanine. 25. The final electron acceptor in the electron transport chain is: a. molecular oxygen. In. H20. 0. cytochrome C. d. UQ. e. NAD'}. 26. All are substrates for gluconeogenesis EXCEPT: a. giycerol. b. lactate. c. acetate. d. pyruvate. 6. most amino acids. 27. All of the enzymes of gluconeogcnesis may be found in the cytosol EXCEPT which is only found in the mitochondria. PEP carboxykinase pyruvate carboxylase fructose—1 ,6—bisphosphatase glucose-(S-phosphatase all are only in cytosol 99*.‘59"? 28. When a cell with the pentose phosphate pathway has need for more pentose phosphates , but no additional NADPH: glucose—6—phosphate dehydrogenase is activated. the oxidative and non—oxidative enzymes of the pentose phosphate pathway are active. the non—oxidative enzymes produce pentose phosphates from fructose 6mphosphate and glyceraldehyde-3—phosphate. _ all enzymes of glycolysis and pentose phosphate pathway are active. none are true. 29. Where in the cell are fatty acids condensed with coenzyme A to form acyl~CoA? a. one? mitochondrial matrix cytoplasm outer mitochondrial membrane or endoplasmic reticulum inner mitochondrial membrane none of the above 30. The main source(s) of NADPH for fatty acid biosynthesis is (are): 99-0579: TCA cycle. oxidative phosphorylation. malic enzyme and the pentose phosphate pathway. the conversion of 0AA to malate by malate dehydrogenase. glycolysis. [30X2 = 60 MARKS] SECTION B: [45 MARKS} 1. What are the chemical reasons for the large negative energy of hydrolysis of phosphoric acid anhydride linkage for compounds such at ATP, ADP, and pyrophosphate? (5) 2. For integral membrane proteins, a—helices play an important role in anchoring the protein to the membrane. Explain why a helix is a thermodynamically stable structural element to embed in a membrane. (5) 3. The weak acid HA is 2% ionized (dissociated) in a 0.2M solution. Calculate the pH of this solution and the equilibrium constant of ionization of HA. (5) 4. ATP hydrolysis at pH 7.0 is accompanied by release of a hydrogen ion to the medium A'rp‘lw + H20 3 ADP?” + are? + If if the AGO' for this reaction is ~30.5 kJ/rnol, What is AGO (that is, the free energy change for the same reaction with ail components, including Hi at a standard state of 1 M)? (5) 5. The graph below depicts the changes in concentration of ATP, ADP and Pi, and the overall AG change in the system. interpret this graph in your own words. (5) Fiat? 6. Discuss the hydrophobic effect its contribution to the thermodynamics of the folded structure in proteins. (5) 7. (a) What is the basic unit of the collagen fiber and which groups stabilizes the collagen structure? (2) (b) What condition is associated with the weakening of collagen fibers? (1) (c) The super helical region of collagen has a triplet repeat structure. What is the primary structure of this repeat? (2) 8. What group of amino acids do Histidine and Aspartic acid belong to? Draw the structure of their R—groups (side chains). (3 0) SECTION C: {45 MARKS] l. The following kinetic data were obtained‘for'an enzyme in the abSence of inhibitor (1), and in the presence of two different inhibitors (2) and (3) at 5 mM concentration. Assume [ET] is the same in each experiment. is} (1). (2) ' (3) (111M) u (mmol/mL-sec u (mmol/mL-sec u (mmol/mIs-sec 1 12 4.3 5.5 2 20 8 9 4 29 14 13 5 35 21 16 12 40 26 18 Determine Vmax and Km for the enzyme. (10) 2. Discuss the metabolic fate of pyruvate under aerobic and anaerobic conditions. (15) 3. a. Name three proteins that are subject to the control mechanism of zyrnogen activation b. Why is it necessary or advantageous for the body to make zymogens? (5) 4. (a) Give the names of the three enzymes, and the various cofactors and prostethic groups associated with them, which constitute the pyruvate dehydrogenase enzyme complex. (4) (b) Name the functions of each in (a) above. (4) (0) Describe the sequence of reactions catalyzed by the pyruvate dehydrogenase enzyme complex. (7') ...
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This note was uploaded on 07/27/2011 for the course BIO 216 taught by Professor Dr.meyer during the Spring '09 term at University of Cape Town.

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327216_2009_06_sp (2) - UNIVERSITY OF THE WESTERN CAPE...

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