chapter15 - Chapter 15 Principles of Metabolic Regulation...

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Chapter 15 Principles of Metabolic Regulation Multiple Choice Questions 1. Regulation of metabolic pathways Page: 571 Difficulty: 2 Ans: B Aside from maintaining the integrity of its hereditary material, the most important general metabolic concern of a cell is: A) keeping its glucose levels high. B) maintaining a constant supply and concentration of ATP. C) preserving its ability to carry out oxidative phosphorylation. D) protecting its enzymes from rapid degradation. E) running all its major metabolic pathways at maximum efficiency. 2. Regulation of metabolic pathways Pages: 574-575 Difficulty: 2 Ans: C If the mass action ratio, Q, for a reaction under cellular conditions is larger than the equilibrium constant, K eq , then: A) the reaction will be at equilibrium. B) the reaction will go backward and be endergonic. C) the reaction will go backward and be exergonic. D) the reaction will go forward and be endergonic. E) the reaction will go forward and be exergonic. 3. Regulation of metabolic pathways Pages: 571-573 Difficulty: 2 Ans: A Which one of the following types of mechanisms is not known to play a role in the reversible alteration of enzyme activity? A) Activation by cleavage of an inactive zymogen B) Allosteric response to a regulatory molecule C) Alteration of the synthesis or degradation rate of an enzyme D) Covalent modification of the enzyme E) Interactions between catalytic and regulatory subunits 4. Analysis of metabolic control Pages: 577-580 Difficulty: 2 Ans: E The flux control coefficient for an enzyme in a multistep pathway depends on: A) the concentration of the enzyme itself. B) the concentration of other enzymes in the pathway. C) the levels of regulatory molecules. D) the amounts of substrate molecules present at each step. E) all of the above.
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Chapter 15 Principles of Metabolic Regulation 5. Analysis of metabolic control Pages: 577-580 Difficulty: 2 Ans: E The elasticity coefficient for an enzyme in a multistep pathway depends on: A) the concentration of the enzyme itself. B) the levels of regulatory molecules. C) the amounts of substrate molecules present at each step. D) both A and C. E) both B and C. 6. Coordinated regulation of glycolysis and gluconeogenesis Pages: 582-583 Difficulty: 2 Ans: D Gluconeogenesis must use “bypass reactions” to circumvent three reactions in the glycolytic pathway that are highly exergonic and essentially irreversible. Reactions carried out by which three of the enzymes listed must be bypassed in the gluconeogenic pathway? 1) Hexokinase 2) Phosphoglycerate kinase 3) Phosphofructokinase-1 4) Pyruvate kinase 5) Triosephosphate isomerase A) 1, 2, 3 B) 1, 2, 4 C) 1, 4, 5 D) 1, 3, 4 E) 2, 3, 4 7. Coordinated regulation of glycolysis and gluconeogenesis Page: 587 Difficulty: 2 Ans: D There is reciprocal regulation of glycolytic and gluconeogenic reactions interconverting fructose-6- phosphate and fructose-1,6-bisphosphate. Which one of the following statements about this regulation is not correct?
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chapter15 - Chapter 15 Principles of Metabolic Regulation...

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