Miesfeld Biochemistry Chapter 10

Since the citrate cycle is an aerobic process, where does it occur?

• Cytoplasm
• Mitochondria
• Ribosome
• Endoplasmic reticulum
• None of the above

High levels of succinate would result from a deficiency of which enzyme?

• Citrate synthase
• Isocitrate dehydrogenase
• α-ketoglutarate dehydrogenase
• Succinyl-CoA dehydrogenase
• Succinate dehydrogenase

Citric acid is found in high levels in fruit juices. How would drinking several glasses of orange juice effect the citrate cycle?

• a) The citrate cycle would not occur, since step 1 produces citrate.

• b) Elevated levels of citrate would feed into the cycle to make more ATP equivalents.

• c) Step 1 (citrate synthase) would be bypassed.

• d) The cycle would go in the reverse manner.

• e) b and c

Why does the citrate cycle produce more ATP than glycolysis?

• a) It is an aerobic process.

• b) It indirectly forms ATP through GTP, NADH, and FADH2.

• c) It is a cyclic pathway.

• a and b

• b and c

Why is the citrate considered to be part of aerobic metabolism even though O2 does not explicitly appear in any reaction?

• Because it takes place in the mitochondrion.

• Because it contains four oxidation reactions.

• Because NADH and FADH2 produce lots of ATP when re-oxidized by the electron transport chain.

• Because it produces reduced electron carriers, which are re-oxidized by transferring their electrons ultimately to oxygen.

• Because it produces carbon dioxide in two oxidative decarboxylation reactions.

The rate of the citric acid cycle would be INCREASED under which of the following conditions?

• a) The ADP/ATP ratio is high.

• b) The ADP/ATP ratio is low.

• c) The NAD+/NADH ratio is low.

• d) The concentration of oxaloacetate is low.

• B, C and D

Which of the following are products of pyruvate oxidation via the pyruvate dehydrogenase complex and the citrate cycle? NTP= ATP/GTP/CTP/TTP

• 3 NADH; 2 FADH2; 0 NTP; 2 CO2

• 3 NADH; 2 FADH2; 1 NTP; 2 CO2

• 3 NADH; 1 FADH2; 0 NTP; 4 CO2

• 4 NADH; 1 FADH2; 1 NTP; 3 CO2

• 4 NADH; 2 FADH2; 1 NTP; 2 CO2

In mammalian cells, formation of succinate from succinyl-CoA requires which of the following coenzymes?

• GDP
• ADP
• FAD
• CoA
• NAD+

Shown below is a list of pairs of compounds. In which pair is the second compound produced by an oxidation of the first compound?

• Pyruvate and phosphoenolpyruvate.

• Succinate and fumarate.

• Oxaloacetate and malate.

• Phosphoenolpyruvate and 2-phosphoglycerate.

• 1,3-bisphosphoglycerate and glyceraldehyde-3-phosphate.