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Ch. 15 Lehninger biochem test bank Exam Latest @ 2023
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Ch. 15 Lehninger biochem test bank Exam Latest @ 2023 1. Which of the following does not contribute to the regulation of enzymatic a ctivity? A) Protein phosphorylation B) Allosteric regulation C) Protein stability D) mRNA stability E) DNA stability - Answer E 2. For an enzyme to effectively change its activity in response to a change in substra te concentration, it is most favorable for: A) Km to be less than cellular substrate concentrations. B) Km to be equal to cellular substrate concentrations. C) Km to be greater than cellular substrate concentrations. D) Vmax to be at the diffusion limit. E) The substrate to also be an allosteric effector. - Answer E 3. Reaction steps that are far from equilibrium are good control points in metab olic pathways because A) the net flux through those steps is easily reversed. B) the rate differences between the forward and reverse steps are often small. C) these reactions occur most frequently in the cell. D) these reactions are highly endergonic. E) these reactions are highly exergonic. - Answer E 4. Aside from maintaining the integrity of its hereditary material, the most importa nt 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. - Answer B 5. The most sensitive indicator of the energetic status of the cell is the concentration o f A) AMP. B) ADP. C) ATP. D) cAMP. E) glucose. - Answer A 6. If the mass action ratio, Q, for a reaction under cellular conditions is larger than the equilibrium constant, Keq, 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. - Answer C 7. 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 - Answer A 8. The flux control coefficient for an enzyme in a multistep pathway depen ds 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 - Answer E 9. 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. - Answer E 10. Which of the following is an example of flux regulation, not flux control upon a n increase in blood glucose levels? A) Induction of insulin B) Increased glucose transport into cells C) Induction of the synthesis of hexokinaseThe benefits of buying summaries with Stuvia:
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