Pentose Phosphate Pathway

Question 1

Two main purposes of pentose phosphate pathway (HMP shunt)?

Answer 1

Produce NADPH and ribulose 5 phosphate. In cytoplasm

Question 2

NADPH uses?

Answer 2

Serves as antioxidant and is needed for synthesis of fatty acids

Question 3

Ribulose 5 phosphate fates?

Answer 3

Can be made into glycolysis intermediates(F6P, Glyceraldehyde3P) or precursors of nucleotides

Question 4

What are the two main branches of HMP shunt?

Answer 4

Oxidative and non oxidative

Question 5

Oxidative path

Answer 5

Is irreversible, glyceraldehyde 6 P dehydrogenase is main enzyme. Produces 2 NADPH

Question 6

Non oxidative path

Answer 6

Is reversible. First makes R5P by isomerase. Then some cells turn R5P into glycolysis intermediates. Main enzyme is TK. Needs thiamine.

Question 7

Where is HMP shunt most active?

Answer 7

In erythrocytes. Produces NADPH for oxidation prevention via glutathione

Question 8

Wernicke-Korsakoff

Answer 8

Thiamine deficiency in alcoholics. Confabulation, memory loss

Question 9

Beriberi

Answer 9

Wet in heart, dry in brain.

Question 10

Regulation of PPP

Answer 10

First reaction in oxidative branch is rate limiting, amount of NADP+ is most important factor.

Question 11

NADPH action with glutathione?

Answer 11

Keeps it reduced, to maintain cysteine residues as antioxidant. Keeps hemoglobin in ferrous state. G6P dehydrogenase needed here