Lehninger biochem test bank Chapters 13- 15
Which of the following compounds has the largest negative value for the standard free-energy change (G'°) upon hydrolysis?
Lehninger biochem test bank Chapters 13- 15
Which of the following compounds has the largest negative value for the standard free-energy change
(G'°) upon hydrolysis?
A) Acetic anhydride
B) Glucose 6-phosphate
C) Glutamine
D) Glycerol 3-phosphate
E) Lactose ANSW - A;Which of the following is not true?
A) The carbon adjacent to a carbonyl can be resonance stabilized to form a carbanion.
B) A carbonyl carbon can be made more electrophilic by a nearby metal ion.
C) The carbon adjacent to an imine can be resonance stabilized to form a carbanion
D) Decarboxylation of an -keto acid goes through a carbocation intermediate.
E) A Claisen ester condensation reaction goes through a carbanion intermediate. ANSW - D;The reaction
ATP ---> ADP + Pi is an example of a_______reaction.
A) homolytic cleavage
B) internal rearrangement
C) free radical
D) group transfer
E) oxidation/reduction ANSW - D;All of the following contribute to the large, negative, free-energy
change upon hydrolysis of "high-energy" compounds except:
A) electrostatic repulsion in the reactant.
B) low activation energy of forward reaction.
C) stabilization of products by extra resonance forms.
D) stabilization of products by ionization.
E) stabilization of products by solvation. ANSW - B;The hydrolysis of ATP has a large negative delta G'°;
nevertheless it is stable in solution due to:
,Lehninger biochem test bank Chapters 13- 15
A) entropy stabilization.
B) ionization of the phosphates.
C) resonance stabilization.
D) the hydrolysis reaction being endergonic.
E) the hydrolysis reaction having a large activation energy. ANSW - E;The hydrolysis of
phosphoenolpyruvate proceeds with a delta G'° of about -62 kJ/mol. The greatest contributing factors to
this reaction are the destabilization of the reactants by electostatic repulsion and stabilization of the
product pyruvate by:
A) electrostatic attraction.
B) ionization.
C) polarization.
D) resonance.
E) tautomerization. ANSW - E;Which one of the following compounds does not have a large negative
free energy of hydrolysis?
A) 1,3-bis phosphoglycerate
B) 3-phosphoglycerate
C) ADP
D) Phosphoenolpyruvate
E) Thioesters (e.g. acetyl-CoA) ANSW - B;The immediate precursors of DNA and RNA synthesis in the cell
all contain:
A) 3' triphosphates.
B) 5' triphosphates.
C) adenine.
D) deoxyribose.
E) ribose. ANSW - B;The structure of NAD+ does not include:
A) a flavin nucleotide.
,Lehninger biochem test bank Chapters 13- 15
B) a pyrophosphate bond.
C) an adenine nucleotide.
D) nicotinamide.
E) two ribose residues. ANSW - A;Which of the following is not true for the nicotinamide cofactors?
A) The oxidized form is positively charged.
B) The reduced form has a large extinction coefficient at 340 nm.
C) The oxidized form provides reducing equivalents to other molecules.
D) Oxidation-reduction reactions with nicotinamides usually involve hydride transfer.
E) Enzymes transfer hydrides stereospecifically to one or the other side of the nicotinamide ring. ANSW -
C;Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists
of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of:
A) aerobic metabolism.
B) anabolic metabolism.
C) a net reductive process.
D) fermentation.
E) oxidative phosphorylation. ANSW - D;The conversion of 1 mol of fructose 1,6-bisphosphate to 2 mol
of pyruvate by the glycolytic pathway results in a net formation of:
A) 1 mol of NAD+ and 2 mol of ATP.
B) 1 mol of NADH and 1 mol of ATP.
C) 2 mol of NAD+ and 4 mol of ATP.
D) 2 mol of NADH and 2 mol of ATP.
E) 2 mol of NADH and 4 mol of ATP. ANSW - E;In glycolysis, fructose 1,6-bisphosphate is converted to
two products with a standard free-energy change (G'°) of 23.8 kJ/mol. Under what conditions
(encountered in a normal cell) will the free-energy change (G) be negative, enabling the reaction to
proceed to the right?
A) If the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate.
B) The reaction will not go to the right spontaneously under any conditions because the G'° is positive.
, Lehninger biochem test bank Chapters 13- 15
C) Under standard conditions, enough energy is released to drive the reaction to the right.
D) When there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of
products.
E) When there is a high concentration of products relative to the concentration of fructose 1,6-
bisphosphate. ANSW - D;Glucose labeled with 14C in C-1 and C-6 gives rise in glycolysis to pyruvate
labeled in:
A) A and C.
B) all three carbons.
C) its carbonyl carbon.
D) its carboxyl carbon.
E) its methyl carbon. ANSW - E;If glucose labeled with 14C at C-2 were metabolized in the liver, the first
radioactive pyruvate formed would be labeled in:
A) all three carbons.
B) both A and C.
C) its carbonyl carbon.
D) its carboxyl carbon.
E) its methyl carbon. ANSW - C;Which of the following reactions in glycolysis requires ATP as a
substrate?
A) Hexokinase
B) Glyceraldehyde-3-phosphate dehydrogenase
C) Pyruvate kinase
D) Aldolase
E) Phosphoglycerate kinase ANSW - A;Which of the following reactions in glycolysis produces ATP as a
product?
A) Hexokinase
B) Glyceraldehyde-3-phosphate dehydrogenase
C) Pyruvate kinase
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