Metabolism IV

Question 1

What reaction does Pyruvate Carboxylase catalyze?

Answer 1

Converts Pyruvate to oxaloacetate in the mitochondria so that oxaloacetate can replenish the TCA cycle or be used in gluconeogenesis (p.101)

Question 2

What reaction does Pyruvate Dehydrogenase catalyze?

Answer 2

Converts Pyruvate to Acetyl CoA in the mitochondria to transition from glycolysis to the TCA cycle (p.101)

Question 3

What reaction does Lactic Acid Dehydrogenase (LDH) catalyze?

Answer 3

Converts Pyruvate to lactate in the cytosol via the cori cycle during anaerobic glycolysis (p.101)

Question 4

What cofactor does Alanine aminotransferase require?

Answer 4

B6 (p.101)

Question 5

What cofactor does Pyruvate Carboxylase require?

Answer 5

Biotin (p.101)

Question 6

What cofactors does Pyruvate Dehydrogenase require?

Answer 6

B1, B2, B3, B5, lipoic acid (p.101)

Question 7

What cofactor does Lactic Acid Dehydrogenase require?

Answer 7

B3 (p.101)

Question 8

In what tissues is the Cori Cycle the major pathway of glycolysis?

Answer 8

RBCs, leukocytes, kidney medulla, lens, testes, cornea (p.101)

Question 9

What are the products of the reaction Pyruvate –> Acetyl CoA?

Answer 9

1 NADH and 1 CO2 (p.101)

Question 10

What enzyme catalyzes the reaction of Pyruvate to Acetyl CoA?

Answer 10

Pyruvate dehydrogenase (p.101)

Question 11

What inhibits the enzyme pyruvate dehydrogenase?

Answer 11

ATP, Acetyl CoA, NADH (p.101)

Question 12

What are the products of the Krebs Cycle?

Answer 12

3 NADH, 1FADH2, 2CO2, 1GTP per acetyl CoA = 10 ATP per Acetyl CoA

Question 13

Where does the TCA cycle occur?

Answer 13

Mitochondria (p.101)

Question 14

What cofactors are required by both the a-ketoglutarate dehydrogenase complex and the pyruvate dehydrogenase complex?

Answer 14

B1, B2, B3, B5, lipoic acid (p.101)

Question 15

What is the starting substrate in the TCA cycle?

Answer 15

Citrate (p.101)

Question 16

What is the ‘end substrate’ in the TCA cycle?

Answer 16

Oxaloacetate (p.101)

Question 17

How do NADH electrons from glycolysis enter the mitochondria for use in the ETC?

Answer 17

Via the malate-aspartate or glycerol-3-phosphate shuttle (p.102)

Question 18

What ETC complex are NADH electrons transferred to?

Answer 18

To complex I of the ETC (p.102)

Question 19

What ETC complex are FADH2 electrons transferred to?

Answer 19

FADH2 electrons are transferred to complex II (at a lower energy level than NADH) (p.102)

Question 20

How is ATP produced by the ETC?

Answer 20

Passage of electrons results in the formation of a proton gradient that is coupled to oxidative phosphorylation to drive ATP production (p.102)

Question 21

What ETC complex is inhibited by Cyanide and CO?

Answer 21

Complex IV (p.102)

Question 22

What ETC complex is inhibited by Oligomycin?

Answer 22

Complex V (p.102)

Question 23

How much ATP is produced via ATP synthase in the ETC?

Answer 23

1 NADH –> 3 ATP; 1 FADH2 –> 2 ATP (p.102)

Question 24

How do electron transport inhibitors poison the ETC?

Answer 24

Directly inhibit electron transport causing a decreased proton gradient and blocking ATP synthesis (p.102)

Question 25

Name four electron transport inhibitors.

Answer 25

Rotenone, cyanide, antimycin A, CO (p.102)