The Citric Acid Cycle

Question 1

Krebs cycle
A. Is the second stage of cellular respiration.
B. It is a series of reactions in mitochondria that oxidize acetyl residues.
C. The acetyl groups are fed into the citric acid cycle are oxidized to form carbon dioxide.
D. The products of the CAC are 3NADH, 1FADH2, 1 GTP(ATP) and CO2
E. All of the above are true

Answer 1

E. All of the above are true

Question 2

Using T(True) or F(False) determine whether the following statements are T/F.
1.The CAC is basically the oxidation of acetyl groups to CO2.
2. The energy of the CAC given out is conserved in the reduced carrier molecules formed which are NADH and FADH2.
3. The tricarboxylic acid cycle is the final common pathway for the aerobic oxidation of carbohydrates, lipids and proteins.
4. Pyruvate generated in the cytoplasm by glycolysis is transported across the inner mitochondrial membrane through a pyruvate or H+ symport.
5. Krebs cycle used mitochondrial energy stored due to electrical potential gradient.

Answer 2

All are true

Question 3

The enzyme that catalyzes the oxidation of pyruvate to form CO2 is

Answer 3

Pyruvate dehydrogenase complex

Question 4

The following are mitochondrial enzymes except.
A. Pyruvate dehydrogenase
B. Dihydrolipoamide dehydrogenase
C. Dihydrolipoamide acetyl transferase
D. Thiamine

Answer 4

D. Thiamine

Question 5

Mention the distinct enzymes of the pyruvate dehydrogenase complex.

Answer 5

Pyruvate dehydrogenase, dihydrolipoamide acetyl transferase and dihydrolipoamide dehydrogenase

Question 6

List the coenzyme required to activate the pyruvate dehydrogenase complex.

Answer 6

Thiamine pyrophosphate, Flavin Adenone Dinucleotide, CoA, Nicotinamide Adenine Dinucleotide and Lipoate

Question 7

Indicate which statement is true or false regarding PDH complex.
1. The active site of E1 has bound TPP.
2. The active site of E2 is the point of connection for the prosthetic group lipoate.
3. E3 has bound FADH2 that transfers the H+ to NAD+ forming FAD.
4. The overall reaction is an oxidative decarboxylation.
5. CAC is an irreversible oxidation process which carbonyl group is removed from pyruvate as a molecule of CO2 and the remaining carbons become the acetyl group of acetyl-CoA

Answer 7

All true

Question 8

Mention any thiamine deficiency disorders.

Answer 8

Beriberi, Wernicke-korsakoff and CNS defects

Question 9

Products of the oxidative decarboxylation of pyruvate are

Answer 9

Carbon dioxide and acetyl-CoA