BCH 369 Exam 3 November 6, 2014 Name: ____ ___________________ __________________ eID __________ ________Section I: 20 points (1 point each) 1. The process by which ATP is formed from ADP in glycolysis is referred to as A) substrate- level phosphorylat ion D) photop hosphory lation B) reductio n E) oxidation C) oxidative phosphorylation 2. A reaction that result s in the loss of electrons from a molecule is a(n) _____. A) reductio n D) oxidation B) liga tion E) pho spho roly sis C) hydrolysis 3. The enzymes that catalyze glycolysis are located in the A) cyto sol D) inner mitoch ondria l membra ne B) mitochondrial matrix E) endoplasmic reticulum C) nucleus 4. The ubiquitous chemistry of acetyl-CoA is centered on its high-energy _________________ bond. A) phosphothioester D) thioesterB) ester E) phosphoanhydride C) phosphoester5. The oxidized form of NADH is _____. A) NADH + D) NADH 2 B) NAD + E) none of the above C) NADH Scrambled version A Page 1
BCH 369 Exam 3 November 6, 2014Name: _________________________________________ eID __________________
Section I: 20 points (1 point each)
1. The process by which ATP is formed from ADP in glycolysis is referred to as A) substrate-level phosphorylation D) photophosphorylation B) reduction E) oxidation C) oxidative phosphorylation
2. A reaction that results in the loss of electrons from a molecule is a(n) _____. A) reduction D) oxidation B) ligation E) phosphorolysis C) hydrolysis
3. The enzymes that catalyze glycolysis are located in the
A) cytosol D) inner mitochondrial membrane B) mitochondrial matrix E) endoplasmic reticulum C) nucleus
4. The ubiquitous chemistry of acetyl-CoA is centered on its high-energy _________________ bond. A) phosphothioester D) thioester B) ester E) phosphoanhydride C) phosphoester
6. In the malate aspartate shuttle, _____ is transferred into the mitochondria while _____ is transferred to thecytosol.
A) NADH; NAD + D) malate; aspartate B) NAD +; NADH E) oxaloacetate; aspartate C) malate; oxaloacetate
7. Complexes I and II each transfer electrons to ______.
A) antioxidant B) copper C) matrix D) heme E) Coenzyme Q
8. Nucleoside triphosphates are useful for energy transfer in metabolic processes because the triphosphate bonds are relatively ______.
A) large D) stable B) low energy E) high energy C) bio-compatible
9. ATP contains one ________ bond and two ______ bonds. A) phosphoester; phosphoanhydride D) phosphoester; glycosidic
B) phosphoanhydride; phosphoester E) glycosidic; amide C) amide; phosphoanhydride
10. For eukaryotes, where are the complexes of electron transport located? A) cytosol D) inner mitochondrial membrane B) outer mitochondrial membrane E) mitochondrial matrix C) mitochondrial intermembrane space
11. Which of the following is the metabolic intermediate that condenses with oxaloacetate to form citrate? A) carboxybiotin D) acetyl-CoA
B)cis
-aconitate E) oxalosuccinate C) succinyl-phosphate
12. Glycolysis produces a net of ______ ATP. A) 1 B) 2 C) 3 D) 4 E) more than 4
13. Which of the following terms indicates that the citric acid cycle is both catabolic and anabolic in nature? A) cataplerotic B) amphipathic C) anaplerotic D) diabolic E) amphibolic
14. Which enzyme is involved in substrate level phosphorylation in glycolysis? A) hexokinase D) aldolase B) pyruvate kinase E) None of the above. C) glyceraldehyde-3phosphate dehydrogenase
15. The ETC component that transfers electrons directly to oxygen is ____ . A) NADH dehydrogenase D) Succinate dehydrogenase B) Cytochrome bc 1 E) none of the above
16. Which of the following metabolic conversions is considered to be the major control point of glycolysis? A) Fructose-6-phosphate ! fructose-1,6-bisphosphate B) pyruvate ! lactate C) 2-phosphoglyerate ! phosphoenolpyruvate D) Fructose-1,6-bisphosphate ! dihydroxyacetone phosphate + glyceraldehyde-3-phosphate E) Glucose ! glucose-6-phosphate
17. Cells control or regulate the flux through metabolic pathways by: A) allosteric control of enzymes. B) covalent modification of enzymes. C) genetic control of the concentrations of enzymes. D) all of the above E) none of the above
18. Which of the following statements are true about oxidative phosphorylation? A) Electron transport provides energy to pump protons into the intermembrane space. B) An electrochemical gradient is formed across the inner mitochondrial membrane. C) Potassium and sodium ions form an ionic gradient across the inner mitochondrial membrane. D) A and B E) A, B, and C
19. The reaction that is catalyzed by pyruvate carboxylase is an example of an ______ reaction because itreplenishes the citric acid cycle intermediates that have been siphoned off for biosynthesis.
A) cataplerotic B) anaplerotic C) amphipathic D) amphibolic
20. How many NADH are produced when one acetyl group is oxidized in the citric acid cycle? A) 1 B) 2 C) 3 D) 4 E) more than 4
Section II: 62 points (2 points each)
21. Consider the following metabolic reaction:Succinyl-CoA + Acetoacetate ! Acetoacetyl-CoA + Succinate " G °' = –1.25 kJ/molThe " G °' for the hydrolysis of Succinyl-CoA is –33.9 kJ/mol. What is the " G °' for the hydrolysis ofAcetoacetyl-CoA (Acetoacetyl-CoA ! Acetoacetate + CoA).
A) –35.2 kJ/mol D) +35.2 kJ/mole B) –32.7 kJ/mol E) none of the above C) +32.7 kJ/mol
22. Which statement best describes the biological rationale for the activation of pyruvate carboxylase byacetyl-CoA?
A) Feedback activation enhances flux through glycolysis. B) Enhances gluconeogenesis by signaling that the cell has sufficient 2C reserves C) Increases enthalpy of H-bonds in the solvent water. D) Increases the supply of malonyl-CoA for fatty acid synthesis. E) Feedforward activation enhances the entry of pyruvate through the TCA cycle as Acetyl-CoA.
23. Which of the following pyruvate dehydrogenase enzymes is correctly paired with the coenzyme that isassociated with it?
A) E1: coenzyme A D) E2: NAD +
B) E2: thiamine pyrophosphate E) E3: lipoamide C) E3: FAD
Use the following to answer question 24.
Below is a schematic of the TCA cycle.
24. Which reactions of the TCA cycle generate NADH? A) 1,3,7 D) 3,4,7 B) 3,5,8 E) none of the above are correct C) 1,4,8
25. What makes the reaction catalyzed by citrate synthase highly exergonic? A) hydrolysis of ATP D) conversion from keto to enol tautomer B) hydrolysis of GTP E) hydrolysis of thioester C) decarboxylation reaction
26. The reaction catalyzed by the enzyme aldolase has a " G °' # +23 kJ/mol. In muscle cells, the reaction proceeds in this same, forward direction. How can this occur?
A) The concentration of reactant(s) must be significantly greater than product(s) in cells. B) The concentration of product(s) must be significantly greater than reactant(s) in cells. C) This " G °' means it is thermodynamically favored. D) The enzyme changes the " G of the reaction in cells to something favorable.
27. How does the reaction catalyzed by malate dehydrogenase proceed despite a " G ° $ of 29.7 kJ/mol? A) an elevated [H +] allows the reaction to proceed B) high levels of NAD + allow the reaction to proceed C) concentrations of oxaloacetate are kept very low by rapid use in the subsequent step D) the enzyme is unique in its ability only to catalyze the reaction in one direction E) the enzyme catalyzed reaction under cellular conditions has a much smaller energy of activation
28. In the TCA cycle, the production of fumarate represents a(n) A) reduction D) decarboxylation B) oxidation E) dehydration C) carboxylation
29. Which complex is unable to generate sufficient free energy to power ATP synthesis? A) Complex I
B) Complex II C) Complex III D) Complex IV E) All the complexes are able to generate sufficient free energy.
30. The functional core of Complex III includes: A) cytochrome c 1 , iron-sulfur protein (Rieske protein)
B) cytochrome c 1 , cytochrome b , myoglobin.
C) cytochrome c 1 , cytochrome b , iron-sulfur protein (Rieske protein)
D) all of the above
E) none of the above
31. Consider the following half-reactions: E o ' = –0.315 V NAD + + H + + 2 e – % NADH E o ' = –0.185 V pyruvate + 2 H + + 2 e – % lactateWhat is the " G °' for the following redox reaction?
pyruvate + NADH + H + ! lactate + NAD +
A) -48.2 kJ/mol D) -25.1 kJ/mol B) -12.5 kJ/mol E) none of the above C) -96.5 kJ/mol
32. Which of the following is at a higher level of oxidation than CH 3CHO?
A) CH 3CH 2OH D) CH 3CO 2H
B) CH 3CH 3 E) none of the above
C) CH 2=CH 2
33. Which of the following statements about glycogen is false? A) Glycogen is the storage polysaccharide in skeletal muscle and liver cells. B) UDP–glucose is produced from glycogen by the action of the enzyme phosphorylase.
C) In glycogen breakdown, glucose residues are sequentially removed from the nonreducing ends. D) The breakdown of glycogen in skeletal muscle ultimately supplies glucose-6-phosphate, which can
enter glycolysis to generate ATP. E) Glycogen is a polymer of glucose in &(1! 4) linkages with &(1! 6) linked branches every 8–14
34. The steps in glycolysis that are different than those in gluconeogenesis are catalyzed by the enzymes: A) pyruvate kinase, phosphofructokinase, hexokinase B) pyruvate kinase, aldolase, hexokinase C) pyruvate kinase, phosphofructokinase, triose phosphate isomerase D) all of the above E) none of the above
35. Ubiquinone is a _____ molecule that serves as a _____ electron carrier when fully reduced; cytochromec is a _____ molecule that serves as a _____ electron carrier when fully reduced.
A) hydrophobic; 2; hydrophilic; 1 D) hydrophilic; 2; hydrophobic; 1 B) hydrophobic; 1; hydrophilic; 1 E) hydrophobic; 1; hydrophilic; 2 C) hydrophilic; 2; hydrophobic; 2
36. Gluconeogenesis requires the hydrolysis of ______ATP equivalents per glucose molecule. A) 3 B) 4 C) 5 D) 6 E) 7
37. Consider the following metabolic reaction:Glucose-6-phosphate ! fructose-6-phosphate " G °' = +2.2 kJ/molWhat is the K eq for this reaction at 25°C?
A) 0.602 B) 1.00 C) 03.21 D) 0.412 E) 2.43
38. What are the coenzyme forms that correspond to X and Y in the following gluconeogenic reactioncatalyzed by glyceraldehyde-3-phosphate dehydrogenase?
A) X = FAD, Y = FADH 2 D) X = NADPH + H +,Y = NADP +
B) X = NAD +, Y = NADH + H + E) X = NADH + H +,Y = NAD +
C) X = NADH + H +,Y = NADP +
39. Which of the following is CORRECT concerning the reaction catalyzed by pyruvate dehydrogenase? A) It is an oxidative decarboxylation. B) It is activated by high concentrations of ATP. C) The enzyme contains a pyridoxal phosphate prosthetic group. D) The reaction is an anaplerotic reaction since it can replace citric acid intermediates that are removed for
other pathways. E) The enzyme contains two different types of subunits.
40. If the following reactions were coupled, what would be the overall " G ° $?glucose + Pi glucose-6-phosphate " G°$ = 13.8 kJ/mol
ATP + H2O ADP + Pi " G°$ = -30.5 kJ/mol
A) 44.3 kJ/mol B) 16.7 kJ/mol C) 0 kJ/mol D) -16.7 kJ/mol E) -44.3 kJ/mol
41. Which of the following is the correct half reaction for the oxidation of acetaldehyde? A) acetaldehyde + H 2O ! acetate - + 3H + + 2e - D) ethanol ! acetaldehyde + 2 H + + 2e -
B) acetate - + 3H + + 2e - ! acetaldehyde + H 2O E) acetaldehyde + CO 2 + H + + 2e - ! pyruvate -
C) acetaldehyde + 2 H + + 2e - ! ethanol
42. Amino acids can be converted to _____. A) carbohydrates D) peptides B) fatty acids E) all of the above C) nucleotides
43. Is the reactant in the (unbalanced) reaction shown below being oxidized or reduced?
A) Oxidized B) Reduced
44. A major allosteric regulator of both glycolysis and gluconeogenesis is: A) 2,3 bisphosphoglycerate D) fructose 1,6 bisphosphate B) 1,3 bisphosphoglycerate E) none of the above C) fructose 2,6 bisphosphate
45. Which statement concerning Complex II of the electron transport chain is FALSE? A) This complex oxidizes FADH 2 and reduces coenzyme Q.
B) This complex also oxidizes succinate to fumarate in the TCA cycle.
C) This complex catalyzes a reversible reaction. D) This complex includes a cytochrome heme. E) This complex cannot pump protons from the matrix to the intermembrane space.
46. Which of the following serves as the free energy source for the metabolic conversion of oxaloacetate to phosphoenolpyruvate, which is catalyzed by PEP carboxykinase?
A) hydrolysis of ATP ! ADP + P i C) hydrolysis of an internal phosphoanhydride
B) hydrolysis of ATP ! AMP + PP i! 2P i D) hydrolysis of GTP ! GDP + P i
47. The electrons formed from the oxidation of glucose are A) directly transferred to O 2 during the citric acid cycle. B) transferred to the coenzymes NAD + and FAD. C) transferred to succinate and arachidonic acid. D) A and B E) none of the above
48. Which of the following occurs when the catalytic subunit of ATP synthase is in the tight state? A) ADP and P i bind D) ATP is released
B) ADP and P i are converted to ATP E) none of the above
C) ATP is hydrolyzed
49. The K eq is 0.503 at 25°C for the following reaction. What is the " G °' for this reaction?
D-Glucose-6-phosphate ! D-Fructose-6-phosphate A) –1,700 J/mol D) +1.70 kJ/mol B) –2,870 J/mol E) none of the above C) +143 J/mol
50. The regulated enzymes of the citric acid cycle include _____ . A) malate dehydrogenase D) & –ketoglutarate dehydrogenase B) fumarase E) none of the above C) citrate lyase
51. Which of the following enzymes of the citric acid cycle is inhibited by ATP?
A) &-ketoglutarate dehydrogenase D) citrate synthase B) succinyl-CoA synthetase E) isocitrate dehydrogenase C) malate dehydrogenase
Section III: 18 points (3 points each)
52. How many protons could theoretically be pumped (under standard state conditions) by Complex III permol of QH 2 oxidized, considering the following information?
coenzyme Q + 2H + + 2 e - ! coenzyme QH 2 E o ' # 0.040 V
cytochromec (Fe
3+
) + e-
!
cytochromec (Fe
2+
) E o
'#
0.270 VH+ (outside matrix) ! H+ (inside matrix) " G # -20 kJ/mol A) ' 4 B) 4 < H +' 6 C) 6 < H +' 8 D) 8 < H +
E) Cannot be determined from the information provided.
53. Brazilin, a compound found in aqueous extracts of sappan wood, has been used to treat diabetics in Korea.Brazilin increases the activity of the enzyme that produces fructose-2,6-bisphosphate, and the compoundalso stimulates the activity of pyruvate kinase. (1) What is the effect of adding brazilin to hepatocytes(liver cells) in culture? and (2) Would brazilin be an effective treatment for diabetes?
A) (1) Flow through the glycolytic pathway is increased; (2) It would NOT be an effective treatment fordiabetes.
B) (1) Flow through the glycolytic pathway is decreased; (2) It would NOT be an effective treatment for
diabetes. C) (1) Flow through the glycolytic pathway is increased; (2) It WOULD be an effective treatment fordiabetes.
D) (1) Flow through the glycolytic pathway is decreased; (2) It WOULD be an effective treatment fordiabetes.
54. Consider the following metabolic reaction:3-Phosphoglycerate ! 2-Phosphoglycerate " G °' = +4.40 kJ/molWhat is the " G for this reaction when the concentration of 2-phosphoglycerate is 0.290 mM and theconcentration of 3-phosphoglycerate is 2.90 mM at 37°C?
A) –5.93 kJ/mol B) –1.30 kJ/mol C) –4.40 kJ/mol D) +10.3 kJ/mol E) –1.54 kJ/mol
55. Acetoacetate may be reduced to 3-hydroxybutyrate. Given the data below, which would serve as a betterreducing agent, NADH or FADH 2?
E o ' = -0.346 Acetoacetate + 2 H + + 2 e - <----> 3-hydroxybutyrate -
E o ' = -0.315 NAD + + H + + 2 e - <----> NADH E o ' = 0 FAD + 2 H + + 2 e - <----> FADH 2
A) NADH B) FADH 2
56. Place the following in the correct order:
A) C,B,D,E,A B) E,A,B,D,C C) E,B,A,D,C D) C,D,B,E,A E) B,C,D,A,E
6. D 7. E 8. E 9. A 10. D 11. D 12. B 13. E 14. B 15. C 16. A 17. D 18. D 19. B 20. C 21. B 22. B 23. C 24. E 25. E 26. A 27. C 28. B 29. B 30. C 31. D 32. D 33. B 34. A 35. A 36. D 37. D 38. E 39. A 40. D 41. A 42. E 43. B 44. C
BCH 369 Exam 3 November 6, 2014Name: _________________________________________ eID __________________
Section I: 20 points (1 point each)
1. Nucleoside triphosphates are useful for energy transfer in metabolic processes because the triphosphate bonds are relatively ______.
A) large D) stable B) low energy E) high energy C) bio-compatible
2. The ETC component that transfers electrons directly to oxygen is ____ . A) NADH dehydrogenase D) Succinate dehydrogenase B) Cytochrome bc 1 E) none of the above
C) Cytochrome c oxidase
3. Which of the following metabolic conversions is considered to be the major control point of glycolysis? A) Fructose-6-phosphate ! fructose-1,6-bisphosphate B) pyruvate ! lactate C) 2-phosphoglyerate ! phosphoenolpyruvate D) Fructose-1,6-bisphosphate ! dihydroxyacetone phosphate + glyceraldehyde-3-phosphate E) Glucose ! glucose-6-phosphate
4. The oxidized form of NADH is _____. A) NADH + D) NADH 2
B) NAD + E) none of the above C) NADH
5. The process by which ATP is formed from ADP in glycolysis is referred to as A) substrate-level phosphorylation D) photophosphorylation B) reduction E) oxidation C) oxidative phosphorylation
14. Which of the following statements are true about oxidative phosphorylation? A) Electron transport provides energy to pump protons into the intermembrane space. B) An electrochemical gradient is formed across the inner mitochondrial membrane. C) Potassium and sodium ions form an ionic gradient across the inner mitochondrial membrane. D) A and B E) A, B, and C
15. In the malate aspartate shuttle, _____ is transferred into the mitochondria while _____ is transferred to thecytosol. A) NADH; NAD + D) malate; aspartate B) NAD +; NADH E) oxaloacetate; aspartate C) malate; oxaloacetate
16. Glycolysis produces a net of ______ ATP. A) 1 B) 2 C) 3 D) 4 E) more than 4
17. ATP contains one ________ bond and two ______ bonds.
A) phosphoester; phosphoanhydride D) phosphoester; glycosidic B) phosphoanhydride; phosphoester E) glycosidic; amide C) amide; phosphoanhydride
18. How many NADH are produced when one acetyl group is oxidized in the citric acid cycle? A) 1 B) 2 C) 3 D) 4 E) more than 4
19. Complexes I and II each transfer electrons to ______. A) antioxidant B) copper C) matrix D) heme E) Coenzyme Q
20. Which of the following terms indicates that the citric acid cycle is both catabolic and anabolic in nature? A) cataplerotic B) amphipathic C) anaplerotic D) diabolic E) amphibolic
Section II: 62 points (2 points each)
21. What are the coenzyme forms that correspond to X and Y in the following gluconeogenic reactioncatalyzed by glyceraldehyde-3-phosphate dehydrogenase?
A) X = FAD, Y = FADH 2 D) X = NADPH + H +,Y = NADP +
B) X = NAD +, Y = NADH + H + E) X = NADH + H +,Y = NAD +
22. Which of the following is the correct half reaction for the oxidation of acetaldehyde? A) acetaldehyde + H 2O ! acetate - + 3H + + 2e - D) ethanol ! acetaldehyde + 2 H + + 2e -
B) acetate - + 3H + + 2e - ! acetaldehyde + H 2O E) acetaldehyde + CO 2 + H + + 2e - ! pyruvate -
C) acetaldehyde + 2 H + + 2e - ! ethanol
23. The electrons formed from the oxidation of glucose are A) directly transferred to O
2 during the citric acid cycle.
B) transferred to the coenzymes NAD + and FAD. C) transferred to succinate and arachidonic acid. D) A and B E) none of the above
24. Which of the following serves as the free energy source for the metabolic conversion of oxaloacetate to phosphoenolpyruvate, which is catalyzed by PEP carboxykinase?
A) hydrolysis of ATP ! ADP + P i C) hydrolysis of an internal phosphoanhydride
B) hydrolysis of ATP ! AMP + PP i! 2P i D) hydrolysis of GTP ! GDP + P i
Use the following to answer question 25.
Below is a schematic of the TCA cycle.
25. Which reactions of the TCA cycle generate NADH? A) 1,3,7 D) 3,4,7 B) 3,5,8 E) none of the above are correct C) 1,4,8
26. A major allosteric regulator of both glycolysis and gluconeogenesis is: A) 2,3 bisphosphoglycerate D) fructose 1,6 bisphosphate B) 1,3 bisphosphoglycerate E) none of the above C) fructose 2,6 bisphosphate
27. Consider the following metabolic reaction:Succinyl-CoA + Acetoacetate ! Acetoacetyl-CoA + Succinate " G °' = –1.25 kJ/molThe " G °' for the hydrolysis of Succinyl-CoA is –33.9 kJ/mol. What is the " G °' for the hydrolysis ofAcetoacetyl-CoA (Acetoacetyl-CoA ! Acetoacetate + CoA).
A) –35.2 kJ/mol D) +35.2 kJ/mole B) –32.7 kJ/mol E) none of the above C) +32.7 kJ/mol
28. Which complex is unable to generate sufficient free energy to power ATP synthesis? A) Complex I B) Complex II C) Complex III D) Complex IV E) All the complexes are able to generate sufficient free energy.
29. Which of the following enzymes of the citric acid cycle is inhibited by ATP? A) &-ketoglutarate dehydrogenase D) citrate synthase B) succinyl-CoA synthetase E) isocitrate dehydrogenase C) malate dehydrogenase
30. Consider the following metabolic reaction:Glucose-6-phosphate ! fructose-6-phosphate " G °' = +2.2 kJ/molWhat is the K eq for this reaction at 25°C?
A) 0.602 B) 1.00 C) 03.21 D) 0.412 E) 2.43
31. Which of the following occurs when the catalytic subunit of ATP synthase is in the tight state? A) ADP and P i bind D) ATP is released
B) ADP and P i are converted to ATP E) none of the above C) ATP is hydrolyzed
32. Which of the following statements about glycogen is false? A) Glycogen is the storage polysaccharide in skeletal muscle and liver cells. B) UDP–glucose is produced from glycogen by the action of the enzyme phosphorylase. C) In glycogen breakdown, glucose residues are sequentially removed from the nonreducing ends. D) The breakdown of glycogen in skeletal muscle ultimately supplies glucose-6-phosphate, which can
enter glycolysis to generate ATP. E) Glycogen is a polymer of glucose in &(1! 4) linkages with &(1! 6) linked branches every 8–14
residues.
33. The functional core of Complex III includes: A) cytochrome c 1 , iron-sulfur protein (Rieske protein)
B) cytochrome c 1 , cytochrome b , myoglobin.
C) cytochrome c 1 , cytochrome b , iron-sulfur protein (Rieske protein)
34. The K eq is 0.503 at 25°C for the following reaction. What is the " G °' for this reaction?
D-Glucose-6-phosphate ! D-Fructose-6-phosphate A) –1,700 J/mol D) +1.70 kJ/mol B) –2,870 J/mol E) none of the above C) +143 J/mol
35. Ubiquinone is a _____ molecule that serves as a _____ electron carrier when fully reduced; cytochrome c
is a _____ molecule that serves as a _____ electron carrier when fully reduced. A) hydrophobic; 2; hydrophilic; 1 D) hydrophilic; 2; hydrophobic; 1 B) hydrophobic; 1; hydrophilic; 1 E) hydrophobic; 1; hydrophilic; 2 C) hydrophilic; 2; hydrophobic; 2
36. The reaction catalyzed by the enzyme aldolase has a " G °' # +23 kJ/mol. In muscle cells, the reaction proceeds in this same, forward direction. How can this occur?
A) The concentration of reactant(s) must be significantly greater than product(s) in cells. B) The concentration of product(s) must be significantly greater than reactant(s) in cells. C) This " G °' means it is thermodynamically favored.
D) The enzyme changes the" G
of the reaction in cells to something favorable.
37. Which statement concerning Complex II of the electron transport chain is FALSE? A) This complex oxidizes FADH 2 and reduces coenzyme Q.
B) This complex also oxidizes succinate to fumarate in the TCA cycle. C) This complex catalyzes a reversible reaction. D) This complex includes a cytochrome heme. E) This complex cannot pump protons from the matrix to the intermembrane space.
38. What makes the reaction catalyzed by citrate synthase highly exergonic?
A) hydrolysis of ATP D) conversion from keto to enol tautomer B) hydrolysis of GTP E) hydrolysis of thioester C) decarboxylation reaction
39. If the following reactions were coupled, what would be the overall " G ° $?glucose + Pi glucose-6-phosphate " G°$ = 13.8 kJ/mol
ATP + H2O ADP + Pi " G°$ = -30.5 kJ/mol
A) 44.3 kJ/mol B) 16.7 kJ/mol C) 0 kJ/mol D) -16.7 kJ/mol E) -44.3 kJ/mol
40. Consider the following half-reactions: E o ' = –0.315 V NAD + + H + + 2 e – % NADH E o ' = –0.185 V pyruvate + 2 H + + 2 e – % lactateWhat is the " G °' for the following redox reaction?
pyruvate + NADH + H + ! lactate + NAD +
A) -48.2 kJ/mol D) -25.1 kJ/mol B) -12.5 kJ/mol E) none of the above
C) -96.5 kJ/mol
41. Amino acids can be converted to _____. A) carbohydrates D) peptides B) fatty acids E) all of the above C) nucleotides
42. Which statement best describes the biological rationale for the activation of pyruvate carboxylase byacetyl-CoA?
A) Feedback activation enhances flux through glycolysis.
B) Enhances gluconeogenesis by signaling that the cell has sufficient 2C reserves C) Increases enthalpy of H-bonds in the solvent water. D) Increases the supply of malonyl-CoA for fatty acid synthesis. E) Feedforward activation enhances the entry of pyruvate through the TCA cycle as Acetyl-CoA.
43. How does the reaction catalyzed by malate dehydrogenase proceed despite a " G ° $ of 29.7 kJ/mol? A) an elevated [H +] allows the reaction to proceed B) high levels of NAD + allow the reaction to proceed C) concentrations of oxaloacetate are kept very low by rapid use in the subsequent step D) the enzyme is unique in its ability only to catalyze the reaction in one direction
E) the enzyme catalyzed reaction under cellular conditions has a much smaller energy of activation
44. The steps in glycolysis that are different than those in gluconeogenesis are catalyzed by the enzymes: A) pyruvate kinase, phosphofructokinase, hexokinase B) pyruvate kinase, aldolase, hexokinase C) pyruvate kinase, phosphofructokinase, triose phosphate isomerase D) all of the above E) none of the above
45. Which of the following is at a higher level of oxidation than CH 3CHO?
A) CH 3CH 2OH D) CH 3CO 2H B) CH 3CH 3 E) none of the above
A) C,B,D,E,A B) E,A,B,D,C C) E,B,A,D,C D) C,D,B,E,A E) B,C,D,A,E
53. Acetoacetate may be reduced to 3-hydroxybutyrate. Given the data below, which would serve as a betterreducing agent, NADH or FADH 2?
E o ' = -0.346 Acetoacetate + 2 H + + 2 e - <----> 3-hydroxybutyrate -
E o ' = -0.315 NAD + + H + + 2 e - <----> NADH E o ' = 0 FAD + 2 H + + 2 e - <----> FADH 2
A) NADH B) FADH 2
54. Consider the following metabolic reaction:3-Phosphoglycerate ! 2-Phosphoglycerate " G °' = +4.40 kJ/molWhat is the " G for this reaction when the concentration of 2-phosphoglycerate is 0.290 mM and theconcentration of 3-phosphoglycerate is 2.90 mM at 37°C?
A) –5.93 kJ/mol B) –1.30 kJ/mol C) –4.40 kJ/mol D) +10.3 kJ/mol E) –1.54 kJ/mol
55. Brazilin, a compound found in aqueous extracts of sappan wood, has been used to treat diabetics in Korea.Brazilin increases the activity of the enzyme that produces fructose-2,6-bisphosphate, and the compoundalso stimulates the activity of pyruvate kinase. (1) What is the effect of adding brazilin to hepatocytes(liver cells) in culture? and (2) Would brazilin be an effective treatment for diabetes?
A) (1) Flow through the glycolytic pathway is increased; (2) It would NOT be an effective treatment fordiabetes.
B) (1) Flow through the glycolytic pathway is decreased; (2) It would NOT be an effective treatment fordiabetes.
C) (1) Flow through the glycolytic pathway is increased; (2) It WOULD be an effective treatment fordiabetes.
D) (1) Flow through the glycolytic pathway is decreased; (2) It WOULD be an effective treatment fordiabetes.
6. D 7. A 8. B 9. D 10. D 11. D 12. B 13. D 14. D 15. D 16. B 17. A 18. C 19. E 20. E 21. E 22. A 23. B 24. D 25. E 26. C 27. B 28. B 29. E 30. D 31. B 32. B 33. C 34. D 35. A 36. A 37. D 38. E 39. D 40. D 41. E 42. B 43. C 44. A
BCH 369 Exam 3 November 6, 2014Name: _________________________________________ eID __________________
Section I: 20 points (1 point each)
1. The oxidized form of NADH is _____. A) NADH + D) NADH 2
B) NAD + E) none of the above C) NADH
2. Which of the following statements are true about oxidative phosphorylation? A) Electron transport provides energy to pump protons into the intermembrane space. B) An electrochemical gradient is formed across the inner mitochondrial membrane. C) Potassium and sodium ions form an ionic gradient across the inner mitochondrial membrane. D) A and B E) A, B, and C
3. Which of the following metabolic conversions is considered to be the major control point of glycolysis? A) Fructose-6-phosphate ! fructose-1,6-bisphosphate B) pyruvate ! lactate C) 2-phosphoglyerate ! phosphoenolpyruvate D) Fructose-1,6-bisphosphate ! dihydroxyacetone phosphate + glyceraldehyde-3-phosphate E) Glucose ! glucose-6-phosphate
4. In the malate aspartate shuttle, _____ is transferred into the mitochondria while _____ is transferred to thecytosol.
A) NADH; NAD + D) malate; aspartate B) NAD +; NADH E) oxaloacetate; aspartate C) malate; oxaloacetate
5. For eukaryotes, where are the complexes of electron transport located? A) cytosol D) inner mitochondrial membrane B) outer mitochondrial membrane E) mitochondrial matrix C) mitochondrial intermembrane space
6. The ubiquitous chemistry of acetyl-CoA is centered on its high-energy _________________ bond. A) phosphothioester D) thioester B) ester E) phosphoanhydride C) phosphoester
7. Nucleoside triphosphates are useful for energy transfer in metabolic processes because the triphosphate bonds are relatively ______.
A) large D) stable B) low energy E) high energy C) bio-compatible
8. Complexes I and II each transfer electrons to ______. A) antioxidant B) copper C) matrix D) heme E) Coenzyme Q
9. The enzymes that catalyze glycolysis are located in the A) cytosol D) inner mitochondrial membrane B) mitochondrial matrix E) endoplasmic reticulum C) nucleus
10. ATP contains one ________ bond and two ______ bonds. A) phosphoester; phosphoanhydride D) phosphoester; glycosidic B) phosphoanhydride; phosphoester E) glycosidic; amide C) amide; phosphoanhydride
11. The reaction that is catalyzed by pyruvate carboxylase is an example of an ______ reaction because itreplenishes the citric acid cycle intermediates that have been siphoned off for biosynthesis.
A) cataplerotic B) anaplerotic C) amphipathic D) amphibolic
12. The process by which ATP is formed from ADP in glycolysis is referred to as A) substrate-level phosphorylation D) photophosphorylation B) reduction E) oxidation C) oxidative phosphorylation
13. How many NADH are produced when one acetyl group is oxidized in the citric acid cycle? A) 1 B) 2 C) 3 D) 4 E) more than 4
14. Glycolysis produces a net of ______ ATP. A) 1 B) 2 C) 3 D) 4 E) more than 4
15. Which enzyme is involved in substrate level phosphorylation in glycolysis? A) hexokinase D) aldolase B) pyruvate kinase E) None of the above. C) glyceraldehyde-3phosphate dehydrogenase
30. The regulated enzymes of the citric acid cycle include _____ . A) malate dehydrogenase D) & –ketoglutarate dehydrogenase B) fumarase E) none of the above C) citrate lyase
31. Is the reactant in the (unbalanced) reaction shown below being oxidized or reduced?
A) Oxidized B) Reduced
32. Which statement concerning Complex II of the electron transport chain is FALSE? A) This complex oxidizes FADH 2 and reduces coenzyme Q.
B) This complex also oxidizes succinate to fumarate in the TCA cycle. C) This complex catalyzes a reversible reaction. D) This complex includes a cytochrome heme. E) This complex cannot pump protons from the matrix to the intermembrane space.
33. The electrons formed from the oxidation of glucose are A) directly transferred to O 2 during the citric acid cycle.
B) transferred to the coenzymes NAD + and FAD. C) transferred to succinate and arachidonic acid. D) A and B E) none of the above
34. Which complex is unable to generate sufficient free energy to power ATP synthesis? A) Complex I B) Complex II C) Complex III D) Complex IV E) All the complexes are able to generate sufficient free energy.
35. Which reactions of the TCA cycle generate NADH? A) 1,3,7 D) 3,4,7 B) 3,5,8 E) none of the above are correct C) 1,4,8
36. Consider the following half-reactions: E o ' = –0.315 V NAD + + H + + 2 e – % NADH E o ' = –0.185 V pyruvate + 2 H + + 2 e – % lactateWhat is the " G °' for the following redox reaction?
pyruvate + NADH + H + ! lactate + NAD +
A) -48.2 kJ/mol D) -25.1 kJ/mol
B) -12.5 kJ/mol E) none of the above C) -96.5 kJ/mol
37. Which of the following is at a higher level of oxidation than CH 3CHO?
A) CH 3CH 2OH D) CH 3CO 2H
B) CH 3CH 3 E) none of the above
C) CH 2=CH 2
38. Gluconeogenesis requires the hydrolysis of ______ATP equivalents per glucose molecule. A) 3 B) 4 C) 5 D) 6 E) 7
39. Consider the following metabolic reaction:Succinyl-CoA + Acetoacetate ! Acetoacetyl-CoA + Succinate " G °' = –1.25 kJ/molThe " G °' for the hydrolysis of Succinyl-CoA is –33.9 kJ/mol. What is the " G °' for the hydrolysis ofAcetoacetyl-CoA (Acetoacetyl-CoA ! Acetoacetate + CoA).
A) –35.2 kJ/mol D) +35.2 kJ/mole B) –32.7 kJ/mol E) none of the above C) +32.7 kJ/mol
40. A major allosteric regulator of both glycolysis and gluconeogenesis is: A) 2,3 bisphosphoglycerate D) fructose 1,6 bisphosphate B) 1,3 bisphosphoglycerate E) none of the above C) fructose 2,6 bisphosphate
41. If the following reactions were coupled, what would be the overall " G ° $?glucose + Pi glucose-6-phosphate " G°$ = 13.8 kJ/mol
ATP + H2O ADP + Pi " G°$ = -30.5 kJ/mol
A) 44.3 kJ/mol B) 16.7 kJ/mol C) 0 kJ/mol D) -16.7 kJ/mol E) -44.3 kJ/mol
42. The functional core of Complex III includes: A) cytochrome c 1 , iron-sulfur protein (Rieske protein)
B) cytochrome c 1 , cytochrome b , myoglobin.
C) cytochrome c 1 , cytochrome b , iron-sulfur protein (Rieske protein)
D) all of the above
E) none of the above
43. How does the reaction catalyzed by malate dehydrogenase proceed despite a " G ° $ of 29.7 kJ/mol? A) an elevated [H +] allows the reaction to proceed B) high levels of NAD + allow the reaction to proceed C) concentrations of oxaloacetate are kept very low by rapid use in the subsequent step D) the enzyme is unique in its ability only to catalyze the reaction in one direction E) the enzyme catalyzed reaction under cellular conditions has a much smaller energy of activation
44. Which of the following pyruvate dehydrogenase enzymes is correctly paired with the coenzyme that isassociated with it?
A) E1: coenzyme A D) E2: NAD +
B) E2: thiamine pyrophosphate E) E3: lipoamide C) E3: FAD
45. In the TCA cycle, the production of fumarate represents a(n) A) reduction D) decarboxylation B) oxidation E) dehydration C) carboxylation
46. What makes the reaction catalyzed by citrate synthase highly exergonic? A) hydrolysis of ATP D) conversion from keto to enol tautomer B) hydrolysis of GTP E) hydrolysis of thioester C) decarboxylation reaction
47. The reaction catalyzed by the enzyme aldolase has a " G °' # +23 kJ/mol. In muscle cells, the reaction proceeds in this same, forward direction. How can this occur?
A) The concentration of reactant(s) must be significantly greater than product(s) in cells. B) The concentration of product(s) must be significantly greater than reactant(s) in cells. C) This " G °' means it is thermodynamically favored. D) The enzyme changes the " G of the reaction in cells to something favorable.
48. Amino acids can be converted to _____. A) carbohydrates D) peptides B) fatty acids E) all of the above C) nucleotides
49. Ubiquinone is a _____ molecule that serves as a _____ electron carrier when fully reduced; cytochrome c is a _____ molecule that serves as a _____ electron carrier when fully reduced.
A) hydrophobic; 2; hydrophilic; 1 D) hydrophilic; 2; hydrophobic; 1 B) hydrophobic; 1; hydrophilic; 1 E) hydrophobic; 1; hydrophilic; 2 C) hydrophilic; 2; hydrophobic; 2
50. What are the coenzyme forms that correspond to X and Y in the following gluconeogenic reactioncatalyzed by glyceraldehyde-3-phosphate dehydrogenase?
A) X = FAD, Y = FADH 2 D) X = NADPH + H +,Y = NADP +
B) X = NAD +, Y = NADH + H + E) X = NADH + H +,Y = NAD +
C) X = NADH + H+
,Y = NADP+
51. Which of the following occurs when the catalytic subunit of ATP synthase is in the tight state? A) ADP and P i bind D) ATP is released
B) ADP and P i are converted to ATP E) none of the above
C) ATP is hydrolyzed
Section III: 18 points (3 points each)
52. Acetoacetate may be reduced to 3-hydroxybutyrate. Given the data below, which would serve as a better
reducing agent, NADH or FADH 2? E o ' = -0.346 Acetoacetate + 2 H + + 2 e - <----> 3-hydroxybutyrate -
E o ' = -0.315 NAD + + H + + 2 e - <----> NADH E o ' = 0 FAD + 2 H + + 2 e - <----> FADH 2
53. Brazilin, a compound found in aqueous extracts of sappan wood, has been used to treat diabetics in Korea.Brazilin increases the activity of the enzyme that produces fructose-2,6-bisphosphate, and the compoundalso stimulates the activity of pyruvate kinase. (1) What is the effect of adding brazilin to hepatocytes(liver cells) in culture? and (2) Would brazilin be an effective treatment for diabetes?
A) (1) Flow through the glycolytic pathway is increased; (2) It would NOT be an effective treatment fordiabetes.
B) (1) Flow through the glycolytic pathway is decreased; (2) It would NOT be an effective treatment for
diabetes. C) (1) Flow through the glycolytic pathway is increased; (2) It WOULD be an effective treatment fordiabetes.
D) (1) Flow through the glycolytic pathway is decreased; (2) It WOULD be an effective treatment fordiabetes.
54. Arsenate is a phosphate analog and can replace phosphate in the glyceraldehyde 3-P dehydrogenasereaction. What would be the expected effect on the ATP yield in glycolysis in the presence of arsenate?
A) 0 ATP produced D) 3 ATP produced B) 1 ATP produced E) 4 ATP produced C) 2 ATP produced
55. How many protons could theoretically be pumped (under standard state conditions) by Complex III permol of QH 2 oxidized, considering the following information?
coenzyme Q + 2H + + 2 e - ! coenzyme QH 2 E o ' # 0.040 V
cytochrome c (Fe 3+ ) + e - ! cytochrome c (Fe 2+) E o ' # 0.270 VH+ (outside matrix) ! H+ (inside matrix) " G # -20 kJ/mol
A) ' 4 B) 4 < H +' 6 C) 6 < H +' 8 D) 8 < H +
E) Cannot be determined from the information provided.
56. Place the following in the correct order:
A) C,B,D,E,A B) E,A,B,D,C C) E,B,A,D,C D) C,D,B,E,A E) B,C,D,A,E
57. Consider the following metabolic reaction:3-Phosphoglycerate ! 2-Phosphoglycerate " G °' = +4.40 kJ/molWhat is the " G for this reaction when the concentration of 2-phosphoglycerate is 0.290 mM and theconcentration of 3-phosphoglycerate is 2.90 mM at 37°C?
A) –5.93 kJ/mol B) –1.30 kJ/mol C) –4.40 kJ/mol D) +10.3 kJ/mol E) –1.54 kJ/mol
6. D 7. E 8. E 9. A 10. A 11. B 12. A 13. C 14. B 15. B 16. D 17. D 18. E 19. D 20. C 21. A 22. D 23. B 24. D 25. A 26. D 27. B 28. A 29. E 30. D 31. B 32. D 33. B 34. B 35. E 36. D 37. D 38. D 39. B 40. C 41. D 42. C 43. C 44. C
