Pentose Phosphate Shunt

Question 1

what is the purpose of the pentose phosphate shunt in RBC and the liver?

Answer 1

Generate NADPH for antioxidant protection for function of the enzyme glutathione reductase

Question 2

name 3 pathways that rely on NADPH for their function

Answer 2

FA synthesis
Cholesterol synthesis
Glutathione

Question 3

write the first step of the irreversible (redox) pathway of the PPP

Answer 3

Glucose 6P + NADP+ -> 6P gluconate + NADPH
Enzyme: glucose 6P dehydrogenase

Question 4

what are the products of the equation 6P gluconate + NADP -> ____

Answer 4

ribulose 5P + CO2 + NADPH

Question 5

write the equation from the Pentose phosphate shunt that the liver uses for nucleotide synthesis

Answer 5

ribulose 5P + ribulose 5P -> Xylulose 5P + ribose 5P

Question 6

When the irreversible (redox) pathway occurs in the liver only, what is the purpose?

Answer 6

To generate NADPH for fatty acid synthesis and cholesterol synthesis

Question 7

After the liver has synthesized cholesterol through the irreversible (redox) pathway, what can be done with the cholesterol?

Answer 7

Cholesterol can be converted to steroid hormones, Vitamin D, and bile acids/salts

Question 8

What is the second step of the irreversible (redox) pathway?
What enzyme is involved?

Answer 8

6P gluconate + NADP+ -> ribulose 5P + CO2 + NADPH
Enzyme: 6P gluconate dehydrogenase

Question 9

When the reversible portion of the pathway occurs in the liver only, what is the purpose?

Answer 9

Use ribose 5P for nucleotide synthesis

Question 10

What are the following examples of: ATP, GTP, CTP, UTP, NAD+, FAD, NADP+

Answer 10

Nucleotides

Question 11

What reaction occurs in the liver in the reversible portion of the pathway?

Answer 11

Ribulose 5P + ribulose 5P -> Xylulose 5P + ribose 5P (epimerase and isomerase)

Question 12

What is the purpose of the reversible portion of the pathway in RBC?

Answer 12

For fructose 6P and glyceraldehyde 3P to reenter glycolysis

Question 13

reversible portion

Ribulose 5P + Ribulose 5P ->

Answer 13

Xylulose 5P + ribose 5P (epimerase and isomerase)

Question 14

reversible portion in RBC

Xylulose 5P + ribose 5P ->

Answer 14

Glyceraldehyde 3P + Sedoheptulose 7P (transketolase)

Question 15

reversible portion in RBC

Glyceraldehyde 3P + sedoheptulose 7P ->

Answer 15

Fructose 6P + erythrose 4P (transaldolase)

Question 16

reversible portion in RBC

Once glyceraldehyde 3P + sedoheptulose 7P -> fructose 6P + erythrose 4P, what happens to fructose 6P?

Answer 16

Fructose 6P reenters glycolysis

Question 17

Erythrose 4P + Ribulose 5P ->

Answer 17

Glyceraldehyde 3P + fructose 6P

Question 18

Once eythrose 4P + ribulose 5P -> glyceraldehyde 3P + fructose 6P, what happens?

Answer 18

Both glyceraldehyde 3P and fructose 6P reenter glycolysis

Question 19

Where does the pentose phosphate shunt occur within cells?

Answer 19

Cytoplasm

Question 20

Where does the pentose phosphate shunt occur in the body?

Answer 20

Liver and RBC

Question 21

What are the two pathways of the pentose phosphate shunt?

Answer 21

Irreversible and reversible

Question 22

How does the liver use NADPH?

Answer 22

Antioxidant protection for function of glutathione reductase
Fatty acid and cholesterol synthesis

Question 23

How do RBC use NADPH?

Answer 23

Antioxidant protection for function of glutathione reductase

Question 24

Name 2 sugars that are produced together in the reversible pathway

Answer 24

(any P that add to 10)
- ribulose 5P + ribulose 5P
- xylulose 5P + ribose 5P
- glyceraldehyde 3P + sedoheptulose 7P
- fructose 6P + erythrose 4P