Ch 26. Pentose Pathway

Question 1

What is Phase 1 of the pentose phosphate pathway?

Answer 1

Oxidative generation of NADPH

Question 2

What is Phase 2 of the pentose phosphate pathway?

Answer 2

Nonoxidative interconversion of sugars

Question 3

What is the net reaction of phase 1?

Answer 3

6carbon > 5carbon + 2NADPH + CO2

Question 4

What is the net reaction of phase 2?

Answer 4

3-5carbon > 2-6carbon + 3carbon

Question 5

What is the rate limiting step of phase 1 of pentose phosphate pathway?

Answer 5

G6P dehydrogenase

Question 6

What does a transketolase do?

Answer 6

Transfers 2 carbon molecule

Question 7

What does a transaldolase do?

Answer 7

Transfers 3 carbon molecules

Question 8

What are the 4 modes of PPP and glycolysis being interconnected?

Answer 8

R5P needs exceed NADPH needs
R5P and NADPH needs balanced
NADPH needs exceed R5P needs
NADPH and ATP needed

Question 9

What happens when R5P needs exceed NADPH needs?

Answer 9

Glycolytic intermediates F6P and glyceraldehyde-3P used by nonoxidative phase of PPP

Question 10

What happens when R5P and NADPH needs are balanced?

Answer 10

G6P enters oxidative phase of PPP to produce NADPH and R5P

Question 11

What happens when NADPH needs exceed R5P needs?

Answer 11

G6P enters oxidative phase of PPP to produce NADPH and R5P
Hexoses and trioses produced from nonoxidative phase used as intermediates in gluconeogenesis

Question 12

What happens when NADPH and ATP are needed?

Answer 12

G6P enters oxidative phase of PPP to produce NADPH and R5P
Hexoses and trioses produced from nonoxidative phase used as intermediates in glycolysis

Question 13

What is oxidative phase controlled by?

Answer 13

NADP+

Question 14

What is nonoxidative phase controlled by?

Answer 14

Availability of substrate