Chemistry 3503 Final exam April 17, Student s name:

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1 Chemistry 3503 Final exam April 17, 2008 Student s name: THIS EXAM IS FOR STUDENTS IN D. CRAIG S SECTION. IF YOU ARE IN M. EZE S SECTION THIS EXAM IS NOT FOR YOU. Part I /40 Part II Question 1 /4 Question 2 /6 Question 3 /10 Question 4 /6 Question 5 /4 Question 6 /4 Question 7 /3 Question 8 /3 total /80 Page 1 of 24

2 PART I: Supply you answers to he following questions by filling out the appropriate sections of the bubble sheet provided. Each question is worth 1 point. Answer all questions. Question 1: What is the a-keto acid of the following compound? O H 3 N CH C O CH 2 CH 2 C O O a. pyruvate b. malate c. oxaloacetate d. fumarate e. none of the above Question 2: The following compound is... O C H C C H C O O O a. malate b. citrate c. fumarate d. succinate e. none of the above Page 2 of 24

3 Question 3: In the Urea Cycle the following compound is hydrolyzed to form urea and what other compound? O H 3 N CH C O CH 2 CH 2 CH 2 NH C NH 2 NH 2 a. citrulline b. ornithine c. lysine d. argininosuccinate e. none of the above Question 4: Carboxylation of the following compound yields... O CoA C CH 3 a. propionyl-coa b. succinyl-coa c. pyruvyl-coa d. malonyl-coa e. none of the above Page 3 of 24

4 Question 5: Which of the following reactions does not occur in a muscle cell? a. pyruvate + NADH? lactate + NAD + b. glucose-6-p + H 2 O? glucose + phosphate c. glutamic acid + pyruvate?? -ketglutarate + alanine d. malate + NAD +? oxaloacetate + NADH e. none of the above answers are correct Question 6: What is the key regulator in the determination of the flow through the oxidative branch of the pentose phosphate pathway? a. ratio of [NADPH]/[NADP + ] b. ratio of [acetyl-coa]/[coa] c. ratio of [acetyl-coa]/[acetyl-phosphate] d. ratio of [NADH]/[NAD + ] e. ratio of [NAD + ]/[NADH] Question 7: Choose the correct option. Under starvation conditions, a rise in the [acetyl-coa] in a liver cell results in... a. a decrease in the rate of glycolysis in the liver b. an increase in the rate of glycolysis in the liver c. an increase in the rate of ketone body formation in the liver d. a decrease in the rate of ketone body formation in the liver e. a decrease in the rate of ketone body degradation in the liver Question 8: Which of the following coenzymes is oxidized along with the conversion of succinate into fumarate? a. NAD + b. FAD c. NADP + d. CoA e. none of the above Question 9: Which of the following could be considered to be an anapleurotic reaction? a. fructose-6-phosphate + ATP? fructose-1,6-bisphosphate + ADP b. phosphoenolphosphate + ADP? pyruvate + ATP c. citrullene + aspartic acid + ATP? argininosuccinate + AMP + PPi d. pyruvate + NADH? lactate + NAD + e. none of the above Page 4 of 24

5 Question 10: Which of the following processes are not possible in a liver cell? a. The net conversion of pyruvate into glycogen b. The net conversion of ketogenic amino acids into urea and palmitate (16:0) c. The net conversion of glucogenic amino acidsinto urea and palmitate (16:0) d. The net conversion of arginine into urea and ornithine e. The net conversion of palmitate (16:0) into glucose Question 11: During the process of fatty acid synthesis, acetyl groups are transferred out of the mitochondrial matrix in the form of... a. citrate b. acetyl-coa c. oxaloacetate d. pyruvate e. none of the above Question 12: How many NADH are normally oxidized in the mitochondrial respiratory chain per O 2 consumed? a. 0.5 b. 1 c. 2 d. 4 e. none of the above Question 13: In the complete oxidation of an acetyl group in the Kreb s cycle into CO 2, how many electrons in total are transferred to NAD +? a. 0 b. 2 c. 4 d. 6 e. 8 Page 5 of 24

6 Question 14: In which location does the following reaction predominantly occur? HO H 2 C CH CH COO COO COO H 2 C H 2 C COO COO + HC COO O a. liver cell b. muscle cell c. brain cell d. fat cell e. plant cell Question 15: Consider 1 cycle only of Kreb s. Acetyl-CoA is enriched with 14 C on the methyl carbon of the acetyl unit. Which of the carbons of the malate formed will be enriched with 14 C? a. carbon-1 only b. carbon-2 only c. carbon-3 only d. carbon-4 only e. none of the above answers are correct Question 16: How many moles of NADPH are consumed in the production of one mole of palmitate (16:0) from a sufficient amount of acetyl-coa in a liver cytosol? a. 1 b. 7 c. 8 d. 14 e. 16 Question 17: The decarboxylation and oxidation of malate produces... a. oxaloacetate b. pyruvate c. fumarate d. succinate e. lactate Page 6 of 24

7 Question 18: The? -keto acid of aspartate is... a. oxaloacetate b. pyruvate c. fumarate d. succinate e.? -ketoglutarate Question 19: When converted from anaerobic to aerobic conditions, the rate of glucose consumption by yeast cells... a. increases b. decreases c. does not change d. yeast can not metabolize glucose e. none of the above answers are correct Question 20: In the Kreb s cycle there are 2 reactions which produce CO 2. Which of the following is correct? a. both of these reactions are irreversible under cellular conditions b. both of these reactions are reversible under cellular conditions c. the first of these reactions is reversible and the second is irreversible under cellular conditions d. the first of these reactions is irreversible and the second is reversible under cellular conditions e. both of these reactions can be reversible or irreversible, depending on the particular cellular condition Question 21: Identify the only false option: Hormonal signals integrate and coordinate metabolic activities of different tissues and organs in the mammal. This ensures: a. that allocation of fuels to different tissues and organs is optimized b. that allocation of precursors to different tissues and organs is optimized c. metabolic cooperation among the tissues and organs d. that every organ receives the same amount of glucose as other organs each time e. that each tissue or organ optimally performs its specialized function. Page 7 of 24

8 Question 22: Identify the only false option: In one complete turn of the Citric acid cycle, a. one acetyl CoA molecule (i.e., a set of two carbon atoms) enters the cycle b. one oxaloacetate molecule is used to form one citrate molecule c. two CO 2 molecules leave the cycle d. there is a net loss of one oxaloacetate molecule from the cycle e. one oxaloacetate molecule is regenerated Question 23: Identify the only false option: Prior to the initiation of their regulation functions on metabolism in the mammal, a. A peptide or amine hormone binds to receptor on outside of the cell b. A steroid or thyroid hormone enters the cell and hormone:receptor complex acts in the nucleus. c. A steroid or thyroid hormone:receptor complex acts on the outside of the cell d. Glucagon binds to receptor on outside of the cell and a second messenger is released in the cytosol. e. Epinephrine binds to receptor on outside of the cell and a second messenger is released in the cytosol. Question 24: Identify the only false option: Both heart muscle and skeletal muscle a. can use glucose as energy source b. can survive a lack of oxygen supply over a short (ie several minutes) period of time c. can use free fatty acids as energy source d. can use ketone bodies as energy source e. contain only a small amount of stored glycogen Question 25: Identify the only false option: Hormone-sensitive cells respond to very low concentrations of the hormone because of: a. non-specific hormone-target cell receptor interaction b. high-affinity highly specific binding of hormone to target cell receptor c. high-affinity hormone-target cell receptor interaction d. highly specific high-affinity hormone-receptor interaction e. highly selective high-affinity hormone-receptor interaction Page 8 of 24

9 Question 26: Identify the only false option: The first step in amino acid catabolism: a. Is catalyzed by the enzyme transaminase (aminotransferase) b. Is catalyzed by the enzyme acyltransferase c. Involves different enzymes for different amino acids d. Requires? -ketoglutarate in most cases as amino group acceptor e. Is the transfer of the amino group from the amino acid. Question 27: Identify the only false option: Oxidative deamination occurs in the liver, and: a. Means oxidative removal of amino group. b. Is catalyzed by L-glutamate dehydrogenase c. Is catalyzed by an enzyme that can use NAD + as electron acceptor. d. Is catalyzed by an enzyme present in the mitochondrial matrix in mammals. e. Is catalyzed by an enzyme that is present in the cytosol in mammals. Question 28: Identify the only false option: In most animals: a. Glutamine transports ammonia in the blood stream. b. Ammonia is converted to nontoxic compound before export from extrahepatic tissue to blood c. Ammonia is transported as nontoxic glutamine from extrahepatic tissue to liver and kidneys. d. Ammonia levels in the blood are tightly regulated. e. None of the above options applies Question 29: Identify the only false option: The glucose-alanine cycle effectively ensures the: a. movement of ammonia from muscle to the liver b. movement of pyruvate from muscle to the liver c. movement of alanine from muscle to the liver d. movement of glucose from muscle to the liver e. availability of a gluconeogenesis substrate in the liver Page 9 of 24

10 Question 30: Identify the only correct option: Complete hydrolysis of a triacylglycerol molecule by intestinal lipase yields: a. one molecule of fatty acid and three molecules of glycerol b. one molecule of glycerol and three molecules of fatty acid c. one molecule of fatty acid, one molecule of cholesterol and two molecules of glycerol d. one molecule of fatty acid, three molecules of glycerol, and one molecule of cholesterol e. three molecules of fatty acid, one of sphingosine, and three of glycerol Question 31:. Identify the only correct option: In one round of the? -oxidation reactions: a. There are 4 different enzymatic reactions b. There are 5 different enzymatic reactions c. The first reaction is catalyzed by enoyl CoA hydratase d. The second reaction is catalyzed by acyl CoA dehydrogenase e. The first reaction is catalyzed by beta-hydroxyacyl CoA dehydrogenase Question 32: Identify the only false option: After seven rounds of beta-oxidation reactions on palmitoyl-coa (16:0) as substrate: a. 7 molecules of Coenzyme A are regenerated b. 7 acetyl-coa molecules are formed c. 8 acetyl-coa molecules are formed d. 7 NADH molecules are formed e. 7 FADH 2 molecules are formed Question 33: Identify the only correct option: Succinate dehydrogenase, a. Is the only membrane-bound enzyme in the citric acid cycle b. Is complex III of the mitochondrial oxidative electron transport chain c. Transfers electrons from succinate to NAD + in the electron transport chain d. Does not require FAD as cofactor for optimum function e. Requires cytochrome c as a cofactor for optimum function Question 34: Identify the only false option: In actively respiring mitochondria, a. Dehydrogenases keep the ratio [NADH]/[NAD + ] relatively high b. The energy of electron transfer is used to pump protons out of the mitochondrial matrix. c. The electrochemical energy inherent in this proton gradient is the proton motive force d. Proton-motive force consists of Chemical potential energy plus electrical potential energy e. None of the above options is true Page 10 of 24

11 Question 35: Identify the only false option: Each of the following three, malonyl-coenzyme A, palmitoyl acyl carrier protein (ACP), and acetyl-coa, is: a. An intermediate or precursor in the mechanism of fatty acid synthase multienzyme system b. At a high potential for group transfer c. A high energy compound d. A phospho-ester e. A thio-ester Question 36: Identify the only false option: When isolated mitochondria are suspended in buffer containing ADP + P i, plus an oxidizable substrate (e.g., succinate): a. substrate is oxidized. b. Oxygen is consumed. c. ATP is synthesized. d. Options a, b and c are obligatorily linked. e. Options a, b, c and d emphasize that respiring mitochondria must have leaky inner membranes. Question 37: Identify the only correct option The standard reduction potential of the FMN prosthetic group in NADH dehydrogenase is volt, and that of the oxygen half cell is volt. NADH dehydrogenase (FMN) + 2H + + 2e - NADH dehydogenase (FMNH 2 ) E o = v ½ O 2 + 2H + + 2e -? H 2 O E o = v a. Reduction of oxygen by NADH dehydrogenase is not thermodynamically feasible b. Associated membrane potential difference E o is volt c. Associated membrane potential difference E o is volt d. Associated membrane potential E o is volt e. Associated membrane potential E o is volt Page 11 of 24

12 Question 38: Identify the only false option: During vigorous exercise, very active skeletal muscle preferentially resorts to mobilizing glycogen for energy. This is advantageous to the organism because: a. Phosphorolysis of glycogen first yields glucose 1-phosphate b. Phosphoglucomutase converts Glucose 1-phospate to Glucose 6-phosphate c. Phosphorolysis of glycogen first yields glucose 6-phosphate d. For priming for glycolysis, one less mole of ATP is required per mole glucose derived from phosphorolysis e. There is a net saving in energy by resorting to glycogen phosphorolysis for glucose. Question 39: Identify the only false option: The adenine nucleotide translocase is integral to the mitochondrial inner membrane. a. It binds ADP 3- in the intermembrane space and transports it into the matrix in exchange for ATP 4- simultaneously transported outward b. It moves 4 negative charges out, and 3 negative charges into the matrix c. It is favoured by the proton-motive force, negative inside d. It is an example of energization of active transport by the proton-motive force e. It is an example of a symporter Question 40: Identify the only false option: Thermogenin in new-born mammals and in hibernating animals: a. Is a unique protein in mitochondria in brown fat b. Uncouples electron transport from oxidative phosphorylation c. Leads to cooling down the whole organism d. Provides alternative pathway for protons to re-enter the mitochondrial matrix e. Dissipates the proton-motive force as heat Page 12 of 24

13 Part II: Answer each question in the space provided following it. Answer all questions. The value of each question is given with it. Please be neat - if I can t read your answer I can t mark it. Question 1(4 points): a. A liver cell is fed lactate where carbon-1 is enriched with 14 C. The lactate is being converted into glucose. Which carbon(s) in glucose will be enriched with 14 C. If none will be enriched, indicate so. b. A liver cell is well fed with alanine enriched with 14 C in its? -carbon. It is being converted into palmitate. Which carbons(s) in palmitate will be enriched with 14 C. If none will be enriched, indicate so. c. A liver cell is well fed with alanine enriched with radioactive nitrogen. This nitrogen is being converted into urea. Draw the structure of urea and indicate which nitrogen(s) in the urea will be enriched. If none will be enriched, indicate so. d. A liver cell is producing? -hydroxybutyrate from acetyl-coa where the methyl carbon of the acetyl group is enriched with 14 C. Which carbons(s) in? -hydroxybutyrate will be enriched with 14 C. If none will be enriched, indicate so. Page 13 of 24

14 Question 2 (6 points): Draw the structure of the following compounds as they would exist in their dominant form under cellular conditions. a. citrulline b. 1,3-bisphosphoglycerate c. lactate Page 14 of 24

15 d. citrate e. malonyl-coa (you don t need to show the structure of the CoA part) f. acetoacetate Page 15 of 24

16 Question 3 (10 points): a. In what subcellular location(s) does gluconeogenesis occur? b. Assuming that NADH is worth 3 ATP equivalents and FADH 2 is worth 2, how many ATP equivalents can be produced by the complete catabolism of 1 molecule of glucose in a muscle cell? c. Complex III of the mitochondrial respiratory chain oxidizes what molecule and reduces what molecule? d. Identify a single enzyme catalyzed reaction seen in class that involves the decarboxylation, oxidation and addition of CoA to a substrate molecule. e. What is the name of the class of enzymes that catalyze a reaction whereby NAD + is reduced? Page 16 of 24

17 f. The non-oxidative branch of the pentose phosphate pathway converts pentose-phosphates into what 2 glycolysis intermediates? g. Assuming that NADH is worth 3 ATP equivalents and FADH 2 is worth 2, how many more ATP equivalents can be produced by the complete catabolism of the fatty acid 20:0 than by the complete catabolism of the fatty acid 18:1? 9? h. Assuming that NAD(P)H is worth/equivalent to 3 ATP equivalents and FADH 2 is worth 2, how many ATP equivalents can be produced by the catabolism of 2 alanine molecules into CO 2, H 2 O and urea in a liver cell? i. Consider 3 molecules of glucose entering the pentose phosphate pathway and then getting dumped into glycolysis and then being converted to pyruvate. How many NADPH, NADH and ATP are produced. (Notice that the question did not say ATP equivalents- do not convert NADH or NADPH into ATP equivalents, just give the answer as x NADPH, y NADH and z ATP.) j. Which of the following will yield more ATP equivalents upon its complete catabolism in a liver cell; 3 molecules of glucose or one molecule of the fatty acid 18:0? Page 17 of 24

18 Question 4 (6 points): Draw a series of complete reactions which will allow for the net sustainable conversion of an even carbon numbered fatty acid and the amino acid alanine into the amino acid glutamic acid. Make sure you show how anything that is consumed in the process is regenerated from the alanine and/or the fatty acid (ie complete all the circles ). Do not show how nucleotides or inorganic species are regenerated. Use only reactions seen in class. Use the most simple and direct path possible. Do not show structures. Do not provide the names of the enzymes. Page 18 of 24

19 Question 5 (4 points): Provide a figure that shows how the net sustainable transport of acetyl-coa equivalents out of the mitochondrial matrix and into the cytosol is achieved. Be sure to complete all the circles. Do not show how nucleotides or inorganic species are regenerated. Use only reactions seen in class. Use the most simple and direct path possible. Do not show structures. Do not provide the names of the enzymes. Page 19 of 24

20 Question 6 (4 points). You discover a new electron transport chain-type pathway in some obscure critter that you discovered living under a rock is a swamp somewhere. NADH is oxidized into NAD + and its electrons are transferred sequentially through a series of redox reactions to cyt X, to cyt Y, to cyt Z and finally used to reduce nitrate into nitrite. The relevant half reactions are as follows: NAD + + H + + 2e -? NADH E o ' = -315 mv cytochrome X e -? cytochrome X + E o ' = +276 mv cytochrome Y e -? cytochrome Y + E o ' = +286 mv 3+ cytochrome Z 2 + e -? cytochrome Z 2+ E o ' = +390mV - NO 3 + 2H + + 2e - -? NO 2 + H 2 O E o ' = +420 mv Which individual step in this electron transport chain-type pathway occurs with the largest amount of free energy if [NADH]/[NAD + ] = 19, [cytochrome X + ]/[cytochrome X 3+ ] = 1.4, [cytochrome Y + ]/[cytochrome Y 3+ ] = 2.5, [cytochrome Z 2+ ]/[cytochrome Z 3+ ] = 4.0 and [NO 2 - ]/[NO 3 - ] = 1.7. Calculate? G at a temperature of 25 o C. R = J/molK, F = J/Vmol. Page 20 of 24

21 Question 7 (3 points): Assuming that the mitochondrial matrix is one ph unit more alkaline than the cytosol and the inner mitochondrial membrane has a potential of 150 mv (inside negative), what is the free energy for the transport of one mole of H + out of the mitochondrial matrix? R = J/molK, F = J/Vmol. Page 21 of 24

22 Question 8 (3 points): If the? G o for ATP hydrolysis = kj/mol and [ADP] = 3.5 mm and [P i ] = 3.5 mm, what is the [ATP] at equilibrium at 37 o C? R = J/molK, F = J/Vmol. Page 22 of 24

23 Two extra pages to complete and unfinished questions. Please be sure to indicate which question it is that you are completing. Page 23 of 24

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