quiz7[1] - 04/04/2008 Name: ______________________ 2008...

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Unformatted text preview: 04/04/2008 Name: ______________________ 2008 Biochemistry Quiz 7 Multiple Choice (20 questions: front and back of page) Identify the choice that best completes the statement or answers the question. Calculators are not required and not permitted for this quiz. 2. Which factor does not affect the melting temperature of two complementary nucleic acid strands? A. total number of residues D. identity of strands: DNA or RNA B. number of pyrimidine residues E. number of guanosine residues C. number of adenosine residues 3. What is the enzymatic reaction mechanism of transaldolase? A. acid-base catalysis by histidine to transfer a proton from C2 to C1 positions B. transfer of a phosphate from C1 to C6 by a phosphorylated serine residue C. protonated Schiff base mediates the transfer of a three carbon group D. decarboxylation by nucleophilic attack on the neighboring carbonyl carbon E. thiamine pyrophosphate mediates the transfer of a two carbon group 4. When lactate is available for gluconeogenesis, why is malate not exported from the mitochondria? A. oxidation of lactate to pyruvate regenerates cytosolic NADH for gluconeogenesis B. the malate--ketoglutarate antiporter is inhibited by cytosolic lactate C. oxaloacetate can be tranported across the mitochondrial membrane D. lactate dehydrogenase is coupled to pyruvate kinase to create phosphoenolpyruvate E. oxaloacetate is generated in the cytoplasm by lactate carboxylase 5. The oxidation of glyceraldehyde 3-phosphate is unfavorable under standard conditions. How is this reaction driven to produce 1,3-biphosphoglycerate? A. 1,3-biphosphoglycerate converts to 3-phosphoglycerate and inorganic phosphate B. 1,3-biphosphoglycerate is kept a low concentrations by phosphoglycerate kinase C. glyceraldehyde 3-phosphate oxidation is coupled to phosphorylation D. glyceraldehyde 3-phosphate dehydrogenase reduces the standard free energy, G' E. glyceraldehyde 3-phosphate oxidation is coupled to NAD+ reduction 6. What is the Pasteur effect? A. increase in cellular ATP concentration when O2 is given to cells grown anaerobically B. partial sterilization of liquids by heating or irradiation with ultraviolet light C. reduction in glucose consumption when O2 is given to cells grown anaerobically D. increase in AMP concentration when ATP is depleted by cellular metabolism E. stereospecificity of substrate binding affinity at the active site of an enzyme 7. Which of the following is a "futile cycle" or substrate cycle? A. phosphofructokinase and fructose-1,6-biphosphatase B. pyruvate carboxylase and phosphoenolpyruvate carboxykinase C. aldolase and triose phosphate isomerase D. transketolase and transaldolase E. biphosphoglycerate mutase and 2,3-biphosphoglycerate phosphatase 1 Name: ______________________ 8. What drives the anhydride exchange reaction of UDP-glucose pyrophosphorylase? A. hydrolysis of UTP during nucleophilic attack by glucose 1-phosphate B. coupling to ATP hydrolysis by nucleoside diphosphate kinase C. subsequent hydrolysis of glycosidic bond by glycogen synthase D. subsequent epimerization of UDP-glucose to UDP-glactose E. subsequent hydrolysis of pyrophosphate by inorganic pyrophosphatase 9. Which of the following is not an allosteric regulator of pyruvate kinase? A. ATP D. fructose 2,6-biphosphate B. alanine E. fructose 1,6-phosphate C. acetyl CoA 10. Which of the following is not an allosteric regulator of phosphofructokinase-1? A. citrate D. fructose 6-phosphate B. ATP E. fructose 2,6-biphosphate C. AMP Reference Diagram for Metabolism 11. This is not a question. 2 ...
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