Biology 638 Biochemistry II Exam-2

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1 Biology 638 Biochemistry II Exam-2 Biol 638, Exam-2 (Code-1) 1. Assume that 16 glucose molecules enter into a liver cell and are attached to a liner glycogen one by one. Later, this glycogen is broken-down to produce 32 glucose molecules. How many ATP molecules are utilized in the glycogen synthesis and breakdown? Select the closest one. a. 0 b. 8 c. 16 d. 32 e Glucose transporters on are regulated by insulin signal. a. liver cells b. brush-border cells c. erythrocytes d. muscle cells e None of the above 3. Glycogen debranching and branching are different pathways because. a. glycogen phosphorylase cannot cleave glucose units in the limit branch b. the reverse process of the branching is an endergonic. c. the debranching process is exergonic but the branching process is endergonic d. the debranching process produces G1P whereas the branching process requires UDPglucose 4. Peter Mitchell s chemiosmotic hypothesis was largely supported by uncoupling agents, because these uncoupling agents disrupt between processes in mitochondrion. a. H 2 O oxidation and ADP phosphorylation b. O 2 reduction and ADP phosphorylation c. NADH oxidation and O 2 reduction d. proton flow and rotation of the αβ subunits of ATP synthase 1

2 Biol 638, Exam-2 (Code-1) The figure to the right is the citric acid cycle pathway. Using the figure, answer the following two questions. 5. Which process produces the third CO 2 in the citric acid cycle? a. E3 b. E4 c. E5 d. E6 e. E7 Pyruvate E0 M0 6. What is M6? a. Oxaloacetate b. Succinyl-CoA c. Succinate d. Fumarate M7 E8 M8 E1 Citrate E2 M2 E7 E3 M6 M3 E6 E4 M5 E5 M4 7. Assume that glucose is completely oxidized through glycolysis and the citric acid cycle in a mammalian cell. The produced NADH and FADH 2 are used to produce ATP from ADP and P i by oxidative phosphorylation. The energy efficiency of the oxidative phosphorylation process is 60%. mol of ATP is produced from one mol of glucose oxidation to CO 2. Don t forget to add ATP and GTP produced in glycolysis and the citric acid cycle. Assume that Farady constant F is 100,000 J V -1 mol -1 and the standard reduction potentials are: ½O 2 + 2H + + 2e - H 2 O (E = 0.8V) NAD+ + H+ + 2e - NADH (E = -0.3V) FAD + 2H + + 2e - FADH 2 (E = -0.1 V) ATP + H 2 O ADP + P i (ΔG = -30 kj/mol) Select the closest one. a. 40 b. 45 c. 50 d. 55 e. 60 2

3 12. If glucokinase in liver is suddenly changed to hexokinase,. a. the glucagon concentration in blood would be increased b. the glucose concentration in blood would be decreased c. the glycogen breakdown in liver would be increased d. the G6P concentration in liver would be increased 13. The followings are some characteristics of glycogen phosphorylase. 3 Biol 638, Exam-2 (Code-1) 8. Assume that an experiment of the oxidative phosphorylation in mitochondria was carried out in a biocell. Oligomycin B was added in the reaction chamber until the O 2 consumption is stopped. Which agent can restart the O 2 consumption? a. β-hydroxybutylate b. Succinate c. NADH d. 2,4-dinitrophenol For question 9 25, select that statement that contains the most significant mistake(s). If none of (a, b, c, d) does not contain significant mistake(s) (i.e. all statements are correct) and e. is None of the above, then select. 9. The followings are some descriptions of glycogen metabolism. a. In general, glucagon and epinephrine stimulate catabolism, while insulin stimulates anabolism. b. If the phosphorylation site Ser-14 of glycogen phosphorylase is mutated to Ala, this mutated enzyme will be inactive because there is no phosphorylation site. c. Glucagon stimulates glycogen breakdown in liver cells. d. One of the subunits of phosphorylase kinase is calmodulin. e. Phosphorylation of regulatory subunits (α and β) and Ca 2+ binding to δ subunit activate the catalytic γ-subunit of phosphorylase kinase. 10. The followings are some descriptions of glycogen metabolism. a. Phosphorylation of glycogen synthase is translated to inactivation of glycogen synthesis. b. Phosphorylation of phosphoprotein phosphatase inhibitor-1 is translated to inactivation of glycogen synthesis. c. Phosphorylation of G-subunit of phosphoprotein phosphatase-1 by protein kinase A is translated to activation of glycogen synthesis. d. High glucose concentration in liver cells is translated to activation of glycogen synthesis. e. High AMP concentration in muscle cells is translated to activation of glycogen breakdown. 11. Assume that PFK-2/FBPase-2 in heart muscle is suddenly changed to the liver isozyme when this person is sleeping.. a. This person would awake without any serious health problem b. This person would not be able to run c. This person would have slightly low blood glucose level d. This person would have low F2,6P level in heart muscle

4 Biol 638, Exam-2 (Code-1) a. A role of PLP in the glycogen phosphorylase reaction is proton donor. b. A role of PLP in the glycogen phosphorylase reaction is proton acceptor. c. PLP in glycogen phosphorylase is a co-factor enzyme but not a prosthetic group. d. In the glycogen phosphorylase reaction, the cleaved glucose is stabilized by having a half-chair conformation The followings are some characteristics of glycogen metabolism. a. α-adrenoreceptors and β-adrenoreceptors are strongly related to glycogen metabolism, but growth factor receptors are not. b. Phosphoglucomutase has a phosphorylated Ser in the active site. c. In glycogen synthesis, a glucose is attached to the non-reducing end of glycogen. d. In the glycogen debranching process, free glucose is produced. 15. The followings are some descriptions about pyruvate dehydrogenase multiple enzyme complex. Pyruvate dehydrogenase multiple enzyme complex. a. is inhibited by arsenite b. has a TPP coenzyme c. has a FAD coenzyme d. in mammalian cells is regulated by product feed-back and covalent modification 16. The followings are some descriptions about characteristic features of enzymes in citric acid cycles. a. Fluoroacetate is a very toxic compound because it inhibits citrate to isocitrate isomerization. b. Aconitase contains a covalently bound [4Fe-4S] iron-sulfur cluster. c. In the succinyl-coa synthetase reaction, the thioester bond (S~C) energy is transferred to a high energy phosphoanhydride bond (P~O). d. FAD in succinate dehydrogenase is a prosthetic group but not coenzyme. 17. The followings are some descriptions about oxidation of acetyl-coa in the citric acid cycle. a. Oxidation of acetyl group in the citric acid cycle produces 8 pairs of electrons. b. Animal cells can produce fat from acetyl-coa. c. Animal cells cannot produce glucose from acetyl-coa. d. A C1 labeled acetyl-coa and a natural oxaloacetate produce a non-labeled oxaloacetate in one round of the citric acid cycle oxidation. e. If the substrate of the citric acid were acetate instead of acetyl-coa, malate to oxaloacetate conversion would not occur. 18. The followings are some descriptions about the functions of Complex I, II, III, and IV. 4

5 Biol 638, Exam-2 (Code-1) a. Complex II (Succinate-Coenzyme Q reductase) is succinate dehydrogenase complex and pumps protons from matrix to cytosol. b. Complex IV (Cytochrome c oxidase) catalyzes reduction of molecular oxygen. c. Cytochrome c is a peripheral membrane protein and carries one electron between Complex III and IV. d. Coenzyme Q is an electron carrier molecule between Complex I and Complex III. 19. The followings are electron some carriers. carries two electrons at one time. a. CoQ b. 2Fe-2S c. FMNH 2 d. NADH e. None of them 20. The followings are some descriptions of ATP and NAD +. a. When ATP mass action ratio is increased, the ATP production is increased. b. When the [NADH]/[NAD + ] ratio is increased, the ATP production is increased. c. A high level of citrate in mitochondrion suppresses glycolysis in cytosol. d. A diagnostic criterion for myocardial infarction is the presence in the blood of H-type lactate dehydrogenase. e. The γ-subunit of ATP synthase has a slightly bent long helix structure. 21. The followings are some descriptions of enzymes in the citric acid cycle. a. In a reaction, A + B C, the enzyme name is "C synthetase" if an ATP hydrolysis energy is used for the synthesis. b. Excess of acetyl-coa is converted to citrate by ATP-citrate lyase, and this conversion produces an NADH. c. The oxidation of alkane (-C-C-) to alkene (-C=C-) is sufficient to reduce FAD to FADH 2. d. When the oxaloacetate concentration is very low, oxaloacetate is synthesized from pyruvate and CO The followings are some descriptions about regulation of the citric acid cycle. a. The citric acid cycle is regulated by NADH concentration b. The citric acid cycle is regulated by Ca 2+ concentration c. The citric acid cycle is regulated by ATP concentration d. All dehydrogenase enzymes in the citric acid cycle are regulation sites of the citric acid cycle. 23. The followings are some descriptions about the electron transport experiment. inhibit(s) the electron transport in the mitochondrion inner membrane. a. Rotenone b. Antimycin A c. Lack of vitamin C d. Lack of ADP 24. The followings are some descriptions about transportation of small molecules between cytosol and matrix of mitochondrion. 5

6 a. ATP and ADP are transported via ATP-ADP symport b. Pyruvate can pass along with H + through the special transport. c. NADH is transported by malate-aspartate shuttle in mammalian cells. d. Efflux of Ca 2+ is transported by a Na + -Ca 2+ antiport. e. P i is transported via P i -H + symport driven by ΔpH. 25. The followings are some descriptions about cytochromes. a. Cytochrome c looses its red color after a chloroform extraction. b. Cytochrome b 566 has the α band at 566 nm. c. Two His residues coordinate to heme a. d. Complex I does not contain any cytochrome. Biol 638, Exam-2 (Code-1) 6