BCHM462_Spring2018_Exam 3

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Chemistry

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Dec 6, 2023

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BCHM 462-Poulin Metabolism Exam #3 – May 3 rd , 2018 YOUR NAME __________________________ (Last, First, M.I.) STUDENT ID # ________________________ "I pledge on my honor that I have not given or received any unauthorized assistance on this examination (assignment)." I have read the University's Honor Code and will abide by its responsibilities. Signature Page 1 (16 pts.) Page 3 (20 pts.) Page 5 (14 pts.) Page 6 (10 pts.) Page 7 (10 pts.) Page 8 (12 pts.) Page 9 (18 pts.) Total (100 pts.) Initial of last name

Exam 3, BCHM 462 Name: Spring 2018 Page 1 1. For the following question circle the correct answer. (16 pts) I. During the Calvin cycle, when transketolase acts on fructose 6-phosphate and glyceraldehyde 3-phosphate, the products are? a. xylulose 5-phosphate and ribose 5-phosphate. b. xylulose 5-phosphate and erythrose 4-phosphate. c. dihydroxyacetone phosphate and glucose 6-phosphate. d. 3-phosphoglycerate and two molecules of glyceraldehyde 3-phosphate. e. 3-phosphoglycerate and glyceraldehyde 3-phosphate. II. Which statement about the light reactions in photosynthetic plants is FALSE? a. A membrane-bound ATPase couples ATP synthesis to electron transfer. b. No CO 2 is fixed in the light reactions. c. There are two distinct photosystems, linked together by an electron transfer chain. d. The ultimate source of electrons for the process is H 2 O. e. The ultimate electron acceptor is O 2 . III. If the fatty acyl-CoA 14:1Δ7 is completely catabolized to CO 2 and H 2 O through beta- oxidation and the citric acid cycle, what would be the net yield of ATP? (NADH = 2.5 ATP, FADH 2 = 1.5 ATP) a. 90.5 b. 92 c. 92.5 d. 94 e. 94.5 IV. Some athletes believe that dietary carnitine supplements will enhance their ability to perform aerobic exercise. Which statement BEST describes the “scientific” basis of this belief? a. Carnitine is an allosteric activator of carnitine-acyl transferase-2 (CAT II). b. Carnitine enhances the activation of fatty acids to fatty acyl-CoA, thereby increasing the rate of their transport into the mitochondrial matrix. c. Carnitine levels in the cytoplasm are reduced when large amounts of fatty acyl carnitine are transported into the mitochondrial matrix. d. Carnitine activates carnitine-acyl transferase-1 (CAT-I) thereby increasing the rate of transport of fatty acids into the mitochondrial matrix. e. Carnitine is required in the transport of medium and long-chain fatty acids into the mitochondrial matrix, and so increasing the amount of carnitine will increase the rate of transport. S O CoA 14:1 ∆ 7

Exam 3, BCHM 462 Name: Spring 2018 Page 2 V. Which of the following statements about the photosynthetic machinery in green sulfur bacterial is TRUE? a. Green sulfur bacteria have both a cyclic and non-cyclic route for electron transfer at the photosystem. b. Ferredoxin is used for the reduction of NAD + . c. The oxidation of H 2 S to produce elemental sulfur donates electrons to regenerate the reactions center. d. Electron flow through the cytochrome b c 1 complex creates an proton gradient that powers ATP synthesis. e. All of the above. f. None of the above. VI. Which of the following cofactors are required for the conversion of glycine to serine? a. Pyridoxal phosphate b. N 5 -methyltetrahydrofolate c. N 5 , N 10 -methylenetetrahydrofolate d. N 10 -Formyltetrahydrofolate e. Both a. and c. f. Both a. and d. g. Both a. and b. VII. Which compound is NOT considered a “ketone body”? a. 3-hydroxybutyrate b. acetone c. dihydroxyacetone d. b -hydroxybutyrate e. Acetoacetate VIII. Which of the following statements is FALSE about the regulation of acetyl-CoA carboxylase during fatty acid biosynthesis? a. Glucagon signaling leads to phosphorylation and inhibition of ACC. b. Acetyl-CoA acts as an allosteric activator of ACC. c. Palmitoyl-CoA inhibits the activity of ACC. d. Citrate activates ACC activity e. Insulin signaling leads to activation of ACC.

Exam 3, BCHM 462 Name: Spring 2018 Page 3 2. Breakdown of the amino acid isoleucine produces both propionyl CoA and acetyl-CoA as products and involves six steps. The reactions are similar to those involved in the metabolism of other amino acids and in the beta-oxidation of fatty acids. Given the similarity of these reactions, provide the name or structure of the missing reactants required for each step in the boxes provided bellow. (20 pts) COO NH 3 PLP COO O Step 1 COO O S O Step 2 CoA S O S O Step 3 NAD + CO 2 CoA CoA

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