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biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 1 biochemistry exam 3 Biology 020.305 November 15, 2004 Instructions for examination: 1. Print your full name clearly on each page. If there are any pages missing, obtain a new exam. No excuses will be accepted for missing pages. There are a total of 11 pages including: 1 cover (page 1) 8 question (pages 2-9) 1 scrap (page 10) 1 grading (page 11) 2. Write answers clearly and concisely in the space provided. Anything written on the back of the exam will not be graded. Extra space for doodling etc is found on the last page of the exam. If you desire partial credit for anything that is NOT in the answer space provided, you must clearly indicate where we should look for that partial credit. It cannot be on the back of the exam. 3. Exams must be written in blue or black permanent ink. Use of white-out, other corrective liquids, or erasable ink is not permitted. Failure to follow these rules will waive your right to submit the exam for a regrade. REMEMBER THAT ON THE SCANTRON SHEET YOU MUST FILL IN YOUR SOCIAL SECURITY NUMBER, THE TEST FORM (mark "A"), YOUR JHED ID (WebCT login), AND YOUR NAME. If you fail to fill in all of this information correctly, you will be penalized 5 points. 4. Calculators are not necessary and their use is not allowed. When arithmetic calculations are requested, if you are unable to do the calculations manually, set up the solution as completely as possible without actually solving for the final number. 5. This exam is closed note and closed book. Books, notes, etc., are to be placed out of sight before the beginning of the exam and are not to be referred to during the exam. 6. Cheating and misrepresentation of work (including on an exam submitted for regrading) are both violations of academic integrity as outlined in the Constitution of the Undergraduate Academics Ethics Board printed in the Undergraduate Academic Manual. Students are expected to know and abide by the standards of academic integrity. 7. You will be allowed 1 hour and 45 minutes to take this exam. 8. Good Luck! ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 2 THE FIRST 34 QUESTIONS OF THE EXAM ARE TO BE ANSWERED USING THE SCANTRON FORM. REMEMBER THAT YOU MUST FILL IN YOUR SOCIAL SECURITY NUMBER, THE TEST FORM (mark "A"), YOUR JHED ID, AND YOUR NAME. IF YOU FAIL TO DO THIS, YOU RISK LOSING ALL 50 POINTS (IF WE CANNOT DETERMINE THE OWNER OF A SCANTRON FORM), AND WILL BE DOCKED 5 POINTS. USE A #2 PENCIL. TRUE OR FALSE: Fill in the bubble on the scantron form corresponding to the most appropriate answer (A=true; B=false). Remember that if anything about the statement is incorrect, the statement is false. (1 point each) 1. The negative charge of glucose 6-phosphate helps trap the molecule within cells. 2. Isomerization of glucose 6-phosphate to fructose 6-phosphate is catalyzed by triose phosphate isomerase. 3. Fructose 1,6-bisphosphatase is allosterically activated by AMP. 4. The first steps of gluconeogenesis occur in the mitochondrial matrix. 5. Pyruvate is decarboxylated as part of its conversion to acetyl CoA by pyruvate dehydrogenase. 6. Consecutive oxidation, hydration, and oxidation reactions appear in both the TCA cycle and fatty acid synthesis. 7. Succinate dehydrogenase (Complex II of the TCA cycle) does not transport protons across the mitochondrial inner membrane. 8. A large positive standard reduction potential indicates that the oxidized form of the molecule is a good oxidizing agent. 9. The standard used in measurements of the standard reduction potential is 1 atm H2 in equilibrium with 1 M H2O. 10. 2,4-Dinitrophenol is an uncoupler because it dissipates the proton gradient without releasing heat. 11. The F0 subunit of ATP synthase rotates while the F1 subunit remains in place. 12. Because of their interactions with the asymmetric subunit, the three subunits of ATP synthase are asymmetric. 13. Glycogen is stored in granules in the mitochondrial matrix. 14. The glycogen stores of the liver are for use solely by the liver. 15. Fatty acids with double bonds cannot be degraded and used to generate energy. 16. Fatty acid synthesis requires a constant supply of NADPH. 17. Muscle cells lack glucose 6-phosphatase 18. The rate of ATP synthesis powered by the conversion of muscle glycogen to lactate is faster than the rate of ATP synthesis powered by the conversion of muscle glycogen to CO2. ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 3 Multiple Choice. FILL IN THE BUBBLE ON THE SCANTRON SHEET THAT CORRESPONDS TO THE BEST ANSWER. (2 points each) 19. The hydrolysis of an enediol intermediate into methyl glyoxal and inorganic phosphate is an unwanted side reaction in the enzymatic conversion of: A) fructose 6-phosphate to glucose 6-phosphate. B) malonyl CoA to acetyl CoA. C) dihydroxyacetone phosphate to glyceraldehyde 3-phosphate. D) phosphoenol pyruvate to pyruvate. E) Fred to Barney. 20. Phosphorylation of glucose to glucose 6-phosphate: A) takes place only in the liver. B) is referred to as a "priming reaction". C) can be catalyzed by the enzyme hexokinase. D) is the last step of gluconeogenesis. E) all of the above. F) A, B, and C. G) B and C. H) B, C, and D. 21. Multiple reactions in the gluconeogenic pathway: A) use the same enzymes that catalyze the reverse reactions in glycolysis. B) occur in the intermembrane space of the mitochondrion. C) are catalyzed by enzymes allosterically inhibited by ATP. D) take place within the pyruvate decarboxylase complex. E) B and C. F) C and D. 22. Glycolysis requires a supply of: A) glycogen. B) insulin. C) glucagon. D) NAD+ E) NADH 23. Citrate synthase catalyzes formation of citrate from acetyl CoA and: A) malonyl CoA. B) oxaloacetate. C) fumerate. D) isocitrate. E) malate. F) graduate. ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 4 Multiple Choice. FILL IN THE BUBBLE ON THE SCANTRON SHEET THAT CORRESPONDS TO THE BEST ANSWER. (2 points each) 24. The TCA cycle is also called: A) the Krebs cycle. B) the citric acid cycle. C) the hardest working cycle in show business. D) all of the above. E) A and B. F) none of the above. 25. Mobile electron carriers involved in the electron transport chain include: A) NADH. B) Cytochrome c. C) Coenzyme Q. D) molecular oxygen. E) all of the above. F) B and C. G) A, B, and C. 26. The proton gradient across the mitochondrial inner membrane: A) powers fatty acid synthesis. B) creates a pH difference across the membrane. C) creates a membrane potential across the membrane. D) helps move ATP out of the matrix. E) all of the above. F) B, C and D. 27. Half channels: A) are found in subunit b of ATP synthase. B) allow for the protonation and deprotonation of the Glu side chain in the a subunit of ATP synthase. C) are too small in diameter to allow water to flow into them. D) all of the above. E) A and B. F) B and C. G) none of the above. 28. Phosphorylase kinase in muscle: A) phosphorylates glycogen phosphorylase to a more active state. B) phosphorylates glycogen phosphorylase to a less active state C) is activated by a signaling pathway initiated by epinephrine binding the -adrenergic receptor. D) A and C. E) B and C. ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 5 29. To be added to the end of a lengthening glycogen chain, a glucose molecule must first be converted to: A) glucose 1-phosphate. B) glucose 6-phosphate. C) UDP-glucose D) ATP-glucose E) glycogen phosphorylase. 30. Membrane lipoprotein lipases: A) are located on adipocytes and muscle cells. B) release fatty acids from triacylglycerides. C) bind chylomicrons. D) all of the above. E) B and C. F) A and B. G) none of the above. 31. Acetyl CoA can be moved to the cytosol: A) for use in the TCA cycle. B) for use in fatty acid degradation. C) in the form of citrate, which is cleaved into Acetyl CoA and oxaloacetate. D) only after glycogen stores are depleted. E) through the Acetyl CoA-hydroxide antiporter. 32. The greatest amount of stored energy that is available to the average person is in the form of: A) glucose in the blood. B) triacylglycerides in adipose tissue. C) glycogen in the brain.. D) glycogen in the liver. E) proteins in the muscle. 33. Insulin: A) inhibits protein synthesis in muscle. B) inhibits protein degradation in muscle. C) stimulates glucose uptake by adipose tissue. D) stimulates glycogen synthesis in liver. E) A, C, and D. F) B, C, and D. G) C and D. 34. After uptake by the liver, fructose is: A) isomerized to glucose and enters glycolysis. B) cleaved into 3 acetate molecules, each of which is converted to Acetyl CoA. C) phosphorylated into fructose 1-phosphate, cleaved and eventually converted into glyceraldehyde 3phosphate. D) converted into polyfructyl methane. E) metabolically inert. F) the cause of painful itching. ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 6 For the remaining questions, write your answers in the space given. WRITE YOUR ANSWERS! USE BLACK OR BLUE INK TO 35. If fructose 6-phosphate concentrations in a cell increase to a certain point, the molecule fructose 2,6bisphosphate can be synthesized. Rather than being an intermediate in a major metabolic pathway, fructose 2,6bisphosphate is a regulatory molecule. What enzyme does fructose 2,6-bisphosphate allosterically regulate? (2 points) Describe either of the 2 effects that fructose 2,6-bisphosphate has on the activity of the enzyme that it regulates. (Note: More detail than the words "inhibits" or "activates" is required.) (3 points) 36. Pyruvate dehydrogenase, isocitrate dehydrogenase, and -ketoglutarate dehydrogenase are all part of one metabolic pathway, and all are regulated by high concentrations of ATP and NADH. In what metabolic pathway do these enzymes participate? (2 points) What do high concentrations of ATP and NADH indicate about the cell? (2 points) What general effect do ATP and NADH have on these enzymes? (2 points) ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 7 USE BLACK OR BLUE INK TO WRITE YOUR ANSWERS! 37. Some athletes supplement their diets with creatine in the hopes of boosting athletic performance. What is the basis of the hope that increased intracellular levels of creatine would boost performance? (3 points) If the creatine supplements did have a physiological effect, would they be more likely to help someone competing in the 100-meter sprint or in a 26-mile marathon, and why? (3 points) 38. In a study of a person with a metabolic disorder that led to unusually small stores of glycogen, it was discovered that the person had a mutation in the gene encoding the protein glycogenin. Additional experimentation revealed that the enzymatic activity of the mutant glycogenin protein was impaired. What role does glycogenin play in glycogen metabolism? (2 points) What is the enzymatic activity of glycogenin, and why would reduced enzymatic activity lead to reduced glycogen stores? (3 points) ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 8 USE BLACK OR BLUE INK TO WRITE YOUR ANSWERS! 39. Reduction half reactions are shown below with their standard reduction potentials. 2 H+ + 2 e- H2 (Eo = -0.42 V) Pyruvate + 2 H+ + 2 e- lactate (Eo = -0.19 V) FAD + 2 H+ + 2 e- FADH2 (Eo = -0.22 V) NAD+ + H+ + 2 e- NADH (Eo = -0.32 V) Write the balanced reaction for the most energetically favorable (or least energetically unfavorable) oxidationreduction reaction that is possible using two of the four half reactions listed above. (6 points) Write the equation that calculates the standard free energy change (Go ) for the reaction that you wrote above. Use the values given above when appropriate. Define any constants in the equation. (6 points) 40. A proton gradient is not needed for ATP synthase to catalyze the formation of ATP from ADP and Pi. Why then does a cell require a proton gradient to generate a supply of ATP? (3 points) ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 9 41. In adipocytes, triacylglycerides are synthesized from fatty acyl CoA molecules and glycerol 3-phosphate. The triacylglycerides can in turn be hydrolyzed to form glycerol and fatty acids, both of which can be released into the blood and transported to the liver. The fatty acids can also be recombined into new triacylglycerides and remain within the adipocytes. How (or, in what form) are fatty acids transported through the blood to the liver after release from adipocytes? (2 points) Describe the mechanism by which the blood glucose level determines whether fatty acids within an adipocyte are released or recombined into a new triacylglyceride molecule. (4 points) 42. Carnitine is a zwitterionic alcohol involved in a transport process. Carnitine deficiency can cause muscle weakness during prolonged exercise. What transport process is carnitine involved in? Indicate what molecule is transported, where is it moved from and where is it moved to. (3 points) Why would a carnitine deficiency cause muscle weakness during prolonged exercise? (4 points) ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 10 Scrap Page ________ biochemistry exam 3 Biology 020.305 11/15/04 FULL NAME__________________________________ Page 11 Page: Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Points possible: 18 10 10 12 11 11 15 13 Points earned: scantron scantron scantron scantron Total Pages 6-9 50 ________

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