Mastering Biochem: Chapter 12

In glycolysis there is a net gain of _____ ATP. 1 4 2 3 5

2; It takes 2 ATP to produce 4 ATP.

How many NADH are produced by glycolysis?

2; Two NADH molecules are produced by glycolysis.

Place the following sequence of events for the reaction catalyzed by fructose-1,6-phosphate aldolase in the correct order: 1) deprotonation and cleavage to release GAP and enamine products 2) protonation of the enamine 3) conversion of the ketone to the imine derived from lysine 4) hydrolysis to release DHAP

3-1-2-4

Place the following sequence of events for the conversion of GAP to 1,3-bisphosphoglycerate in the correct order: 1) attack by Pi 2) release of cysteine as a free thiol 3) transfer of hydride to NAD+ 4) attack by cysteine at the carbonyl carbon of GAP

4-3-1-2

In glycolysis, what starts the process of glucose oxidation? FADH2 NADPH ATP ADP hexokinase

ATP; Some ATP energy is used to start the process of glucose oxidation.

Which of these is NOT a product of glycolysis? pyruvate FADH2 ATP NADH

FADH2- citric acid cycle

Which of the following are products of glycolysis? 1) ATP 2) pyruvate 3) NAD+ 4) NADP+ Only 1 and 3 are products of glycolysis. Only 2 and 4 are products of glycolysis. Only 1, 2, and 3 are products of glycolysis. Only 1 and 2 are products of glycolysis.

Only 1 and 2 are products of glycolysis.

Which statement about the interconversion of DHAP to GAP is NOT true? a.) The reaction proceeds through an enediol intermediate. b.) The reaction is an oxidation catalyzed by triose phosphate isomerase. c.) The reaction is endergonic. d.) The reaction requires deprotonation on the carbon adjacent to the carbonyl group of DHAP

b; This reaction is an isomerization (the carbonyl group is shifting from C-2 to C-1) and therefore is not an oxidatio

What enzyme catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate? a.) fructose-1,6-bisphosphate aldolase b.) glucose-6-phosphate isomerase c.) phosphofructokinase d.) The reaction is spontaneous and does not require an enzyme to catalyze the reaction.

c

What reaction does glucose-6-phosphatase catalyze? a.) the conversion of glucose-6-phosphate to fructose b.) the conversion of glucose-6-phosphate to glucose-1-phosphate c.) the conversion of glucose-6-phosphate to glucose d.)None of the listed responses is correct.

c

Hexokinase IV has a Km value that is substantially higher than the Km for other hexokinases. What is the significance of this fact? a.) The higher Km reflects higher affinity for its substrate, and therefore this kinase is only operational when glucose levels are low. b.) The higher Km reflects lower affinity for its substrate, and therefore this kinase is only operational when glucose levels are low. c.) The higher Km reflects lower affinity for its substrate, and therefore this kinase is only operational when glucose levels are high. d.) The higher Km reflects high affinity for its substrate, and therefore this kinase is only operational when glucose levels are high.

c; High Km represents lower affinity, and this enzyme would only be active when glucose concentrations are high.

Which of the following statements about the reaction catalyzed by phosphoglycerate kinase is NOT true? a.) This is an example of a substrate-level phosphorylation reaction. b.) The reaction produces ATP to bring the cost of glycolysis to this point to zero. c.) The reaction is exergonic. d.) The phosphate group from C-3 of 1,3-BPG is transferred to ADP.

d; the phosphate at C-3 is a phosphoester--its hydrolysis does not yield sufficient energy to allow the transfer of a phosphate to ADP; the phosphate at C-1 is a mixed phosphoanhydride and therefore does release enough energy for this conversion

In glycolysis, ATP molecules are produced by _____. a.) cellular respiration b.) oxidative phosphorylation c.) photosynthesis d.) photophosphorylation e.) substrate-level phosphorylation

e, substrate-level phosphorylation- A phosphate group is transferred from glyceraldehyde phosphate to ADP.

Which of the following is NOT a fate for pyruvate?

the conversion to malate Explanation: -acetyl coenzyme A: aerobic oxidation through Kreb's cycle (citric acid cycle) . In vertebrates it can be processed in anaerobic respiration: lactate as the end product. In prokaryotes it can be processed in anaerobic respiration: ethanol as the end product. It can be used up in gluconeogenesis: glucose 6 phosphate. But it never produces malate.