Exam 4: Metabolism
The total free-energy change for a chemically related series of reactions equals the: a. sum of the free-energy changes of individual steps. b. difference of the free-energy changes of all steps. c. difference of the free-energy changes between each individual step. d. free-energy changes of an individual step. e. maximum free energy.
a
What is the ultimate product of oxidation in aerobic organisms? a. CO2 b. pyruvate c. H2O d. lactate e. O2
a
What reactions are used to replenish citric acid cycle intermediates after they are depleted by biosynthetic pathways? a. anaplerotic b. amphoteric c. amphibolic d. cataplerosis e. biosynthetic
a
What substance serves as the electron donor for most reductive biosynthetic pathways? a. NADPH b. NAD+ c. FAD d. NADH e. FMN
a
Covalent modification of phosphorylase a to phosphorylase b is catalyzed by: a. calmodulin. b. phosphorylase kinase. c. protein kinase B. d. protein kinase A. e. insulin.
b
High-transfer-potential electrons are captured by the pyruvate dehydrogenase complex in the form of: a. ATP. b. NADH. c. acetyl CoA. d. FADH2. e. acetyllipoamide.
b
What is an allosteric inhibitor of phosphofructokinase? a. fructose 1,6-bisphosphate b. ATP c. AMP d. NADH e. GTP
b
What is the function of glucokinase? a. It supplies fructose 6-phosphate for glycogen synthesis. b. It supplies glucose 6-phosphate for glycogen synthesis and formation of fatty acids. c. It catalyzes the reaction of transformation of glucose 6-phosphate to pyruvate. d. It supplies glucose for glycogen synthesis and formation of fatty acids. e. It catalyzes the reaction of forming glucose from glycogen.
b
What molecule inhibits fructose 1,6-bisphosphatase? a. fructose 6-phosphate b. fructose 2,6-bisphosphate c. fructose 1,6-bisphosphate d. glucose 6-phosphate e. glucose
b
What cytochrome is the only water-soluble cytochrome of the electron-transport chain? a. cytochrome P450 b. coenzyme Q c. cytochrome c d. cytochrome c oxidase e. cytochrome b5
c
What is the name of the mechanism proposed by Peter Mitchell that explains how ATP synthesis and electron transport are coupled? a. proton-motive force hypothesis b. electron transport hypothesis c. chemiosmotic hypothesis d. ATP recycling hypothesis e. oxidative phosphorylation hypothesis
c
What reaction does glyceraldehyde 3-phosphate dehydrogenase catalyze? a. conversion of fructose 6-phosphate into glucose 6-phosphate b. conversion of 1,3-bisphosphoglycerate into 3-phosphoglycerate c. conversion of glyceraldehyde 3-phosphate into 1,3-bisphosphoglycerate d. conversion of 1,3-bisphosphoglycerate into dihydroxyacetone phosphate e. conversion of glucose 6-phosphate into fructose 6-phosphate
c
Choose the FALSE statement concerning the regulation of the pentose phosphate pathway. a. Low levels of NADP+ inhibit oxidation of glucose 6-phosphate. b. NADPH competes with NADP+ in the binding active site of glucose 6-phosphate dehydrogenase. c. The level of NADP+ is very important in regulation of the pathway. d. The reaction of dehydrogenation of glucose 6-phosphate does not influence the rate of the whole pathway. e. The nonoxidative phase of the pathway is primarily controlled by the availability of the substrates.
d
Inhibitory factor 1: a. inhibits apoptosis. b. stops the process of the malate-aspartate shuttle. c. stops the transfer of electrons in respiration. d. prevents the wasteful hydrolysis of ATP. e. takes part in generating heat from ATP synthesis.
d
What class of enzymes catalyzes the reaction of transferring a phosphoryl group from ATP to acceptor? a. amylases b. hydrolases c. phosphatases d. kinases e. phosphorylases
d
What enzymes are tightly associated with FAD or FMN? a. isomerases b. transferases c. lyases d. flavoproteins e. kinases
d
What primer catalyzes the formation of α-1,4-glucose polymers? a. glucose b. calmodulin c. insulin d. glycogenin e. glycogen
d
What molecule inhibits hexokinase activity? a. glucose b. fructose 1,6-bisphosphate c. fructose 2,6-bisphosphate d. fructose 6-phosphate e. glucose 6-phosphate
e
What molecule, which is an intermediate in the citric acid cycle, inhibits phosphofructokinase in the liver? a. glucose 6-phosphate b. fructose 6-phosphate c. oxaloacetate d. isocitrate e. citrate
e
What type of reactions requires energy? a. spontaneous b. biochemical c. chemical d. catabolic e. anabolic
e
