Lecture 10 - Pentose Phosphate Shunt

Question 1

One function of the Pentose Phosphate pathway is recycling of excess pentose phosphates back to _________ and glycolysis. This is especially important in RBCs where there are no biosynthetic reactions.

Answer 1

glyceraldehyde-3-phosphate

Question 2

What is the function of the oxidative phase of the pentose phosphate pathway?

Answer 2

generate NADPH and pentoses

Question 3

What is the function of the non-oxidative phase of the pentose phosphate pathway?

Answer 3

recycle excess pentose phosphates

Question 4

Which phase of the pentose phosphate pathway is irreversible?

Answer 4

oxidative phase

Question 5

Which phase of the pentose phosphate pathway is reversible?

Answer 5

non-oxidative phase

Question 6

The major site of regulation of the pentose phosphate pathway is __________.

Answer 6

glucose-6-P dehydrogenase

Question 7

Glucose-6-P dehydrogenase, a major site of regulation in the pentose phosphate pathway, is inhibited by what two molecules?

Answer 7

1. NADPH
2. fatty acyl-CoA

Note: Inhibition is reversed by oxidized glutathione

Question 8

What condition can occur in individuals deficient in glu-6-P dehydrogenase who are taking antimalarial drugs?

Answer 8

anemia

Question 9

_________ reduces the iron of metHb back to its normal ferrous state and restores hemoglobin’s function as an oxygen carrier.

Answer 9

MetHb Reductase

Question 10

Glutathione Reductase uses _____ to reduce oxidized glutathione back to the reduced form.

Answer 10

NADPH

Question 11

The pentose phosphate pathway is a major source of _____ for biosynthesis.

Answer 11

NADPH

Question 12

The pentose phosphate pathway is a major source of __________ for nucleotide synthesis.

Answer 12

ribose-5-P

Question 13

__________ is the only enzyme in the non-oxidative branch of the pentose phosphate pathway with a coenzyme requirement.

Answer 13

Transketolase - requires thiamine pyrophosphate

Question 14

Transketolase requires a coenzyme that can be used to diagnose Wernick-Korsakoff syndrome. What coenzyme is being referred to?

Answer 14

Thiamine pyrophosphate - deficiency of thiamine in lysed RBCs can be used to detect a thiamine deficiency

Question 15

How do antimalarial drugs increase oxidative stress?

Answer 15

Increased production of toxic oxygen metabolites

Question 16

__________ converts hydrogen peroxide to water and molecular oxygen.

A. MetHb reductase
B. Superoxide dismutase
C. Glutathione peroxidase
D. Glutathione reductase
E. Catalase

Answer 16

E

Question 17

____________ converts superoxide to hydrogen peroxide and oxygen.

A. MetHb reductase
B. Superoxide dismutase
C. Glutathione peroxidase
D. Glutathione reductase
E. Catalase

Answer 17

B

Question 18

_____________ uses NADPH to return glutathione to reduced and functional form.

A. MetHb reductase
B. Superoxide dismutase
C. Glutathione peroxidase
D. Glutathione reductase
E. Catalase

Answer 18

D

Question 19

__________ reduces hydrogen peroxide to water and is the most important enzyme in RB for disposal of peroxide. (Hint: it uses glutathione as a reducing agent.)

A. MetHb reductase
B. Superoxide dismutase
C. Glutathione peroxidase
D. Glutathione reductase
E. Catalase

Answer 19

C

Question 20

___________ catalyzes the conversion of NADPH and oxygen to the superoxide anion.

Answer 20

NADPH oxidase

Question 21

Chronic granulocytic disease is a heritable disease caused by a deficiency in what enzyme?

Answer 21

NADPH oxidase

Question 22

How is the pentose phosphate pathway linked to the activity of phagocytic cells?

Answer 22

Phagocytic cells generate superoxide anions and other reactive oxygen species to kill ingested bacteria.