Exam 4 - Pentose Phosphate

Question 1

What energy molecule does the pentose phosphate pathway produce?

Answer 1

NADPH

Question 2

The Pentose Phosphate Pathway provides [] requierd as a componenet of nucleotides and coenzymes

Answer 2

Ribose

Question 3

What is another name for stage 1 of the Pent-Phos pathway?

Answer 3

Oxidative decarboxylation

Question 4

Stage 1

What enzyme convert glucose 6-phosphate to 6-phosphoglucono-delta-lactone and NADPH

Answer 4

Glucose 6-phosphate dehydrogenase

Question 5

Stage 1

What does 6-phosphogluconolactonase do?

Answer 5

Converts phosphoglucono-delta-lactone to 6-phosphogluconate

Question 6

Stage 1

What enzyme converts 6-phosphogluconate to ribulose 5-phosphate, CO₂, and NADPH?

Answer 6

6-phosphogluconate dehydrogenase

Question 7

Stage 1

What does Ribose 5-phosphate isomerase do?

What is the other name for this enzyme?

Answer 7

• converts ribulose 5-phosphate to ribose 5-phosphate
• Pentose phosphate isomerase

Question 8

What enzymes produce NADPH during the pentose phosphate pathway?

Answer 8

1. Glucose 6-phosphate dehydrogenase
2. 6-phosphogluconate dehydrogenase

Question 9

Are the reactions of stage 1 freely reversible?

Answer 9

Negative

Question 10

What is the summary equation of stage 1?

Answer 10

Glucose 6-P + 2 NADP⁺ + H₂O

——>

Ribulose 5-P + 2 NADPH + CO₂

Question 11

Stage 2 recycles ribulose 5-P to [] intermediates…

Answer 11

glycolytic

Question 12

Are the reactions of Stage 2 freely reversible?

Answer 12

Yes

Question 13

What does Phosphopentose Epimerase do?

What is another name for this enzyme….

Answer 13

Interconverts ribulose 5-P and xylulose 5-P

Pentose Phosphate Epimerase

Question 14

What does the first transketolase do in Stage 2 of the Pentose Phosphate Pathway?

Answer 14

• transfers a two-carbon unit of ketose (xylulose 5-P) to an aldose (ribose 5-P) acceptor
• This creates
  
  • Glyceraldehyde 3-P
  • Sedheptulose 7-P

Question 15

Which enzyme transfers a three carbon unit of sedoheptulose 7-P to glyceraldehyde 3-P to form fructose 6-P and erythrose 4-P??

Answer 15

Transaldolase

Question 16

What does the 2nd Transketolase do in Stage 2 of the Pentose Phosphate Pathway?

Answer 16

• transfers a two-carbon unit of ketose (xylulose 5-P) to an aldose (erythrose 4-P) acceptor
• This creates
  
  • Glyceraldehyde 3-P
  • Fructose 6-P

Question 17

What is the summar equation for Stage 2 of the Pent-Phos Path?

Answer 17

3 Ribulose 5-P

—>

<—

2 Fructose 6-P + Glyceraldehyde 3-P

Question 18

Whag is the summary equation for Stages 1 and 2?

Answer 18

Glucose 6-P + 12 NADP⁺

—>

6 CO₂ + 12 NADPH

Question 19

Why is Erythrose 4-P important and what is the pathway for its “importance”???

Answer 19

• It is used to make tyrosine in humans
• Erythrose 4-P —> Shikimate
  
  • Shikimate acid Pathway
• Shikimate —> Chorismate
  
  • Chorismate Biosyn
• Chorismate —> Phenylalanine
• Phenylalanine —> Tyrosine