Pentose Phosphate Pathway

Question 1

What is another name for pentose phosphate pathway (PPP)?

Answer 1

Hexose monophosphate shunt (HMP) or Phosphogluconate pathway

Question 2

Where does the pentose phosphate pathway occur?

Answer 2

In the cytosol

Question 3

What is the purpose of the pentose phosphate pathway?

Answer 3

To produce NADPH and ribose-5-phosphate

Question 4

In which tissues is the pentose phosphate pathway highly active?

Answer 4

Liver / Adipose tissue / Adrenal cortex / Lactating mammary gland

Question 5

Which vitamin is NADPH associated with?

Answer 5

Vitamin B3

Question 6

How many stages are in the PPP and what are they?

Answer 6

2 stages
Stage 1 : Oxidative phase
Stage 2 : Non-oxidative phase

Question 7

True or False: the oxidative phase consists of reversible reactions

Answer 7

False, it consists of 3 irreversible reactions

Question 8

What are the products of the oxidative phase of the pentose phosphate pathway?

Answer 8

2 NADPH / 1 CO2 / 1 ribulose 5-phosphate

Question 9

What are the tissues is which NADPH is used to synthesize fatty acids?

Answer 9

Liver / Lactating mammary glands / Adipose tissue

Question 10

What are the tissues is which NADPH is used to synthesize steroid hormones?

Answer 10

Testes / Ovaries / Placenta / Adrenal cortex

Question 11

True or False : when the pathway starts with the oxidative phase , it must go through the non-oxidative phase

Answer 11

True

Question 12

What is the main purpose of PPP in erythrocytes?

Answer 12

It generates NADPH which is used to reduce glutathione to prevent accumulation of hydrogen peroxide

Question 13

What happens in the oxidative phase of PPP?

Answer 13

Glucose 6 -phosphate is converted into ribulose 5- phosphate

Question 14

How many NADPH molecules are generated during the oxidative phase?

Answer 14

2 NADPH molecules

Question 15

How many reactions does the first step consist of?

Answer 15

3 reactions

Question 16

Glucose 6-phosphate is converted to 6-phosphogluconolactone by which enzyme?

Answer 16

Glucose 6-phosphate dehydrogenase (G6PD)

Question 17

Glucose 6- phosphate dehydrogenase is the enzyme which……

Answer 17

Oxidizes glucose 6-phosphate to 6-phosphogluconolactone

Question 18

What is the main allosteric inhibitor of glucose-6-phosphate dehydrogenase?

Answer 18

NADPH

Question 19

What is the major regulatory step in the pentose phosphate pathway?

Answer 19

The conversion of glucose-6-phosphate and NADP+ to 6-phosphogluconolactone and NADPH by the enzyme glucose-6-phosphate dehydrogenase.

Question 20

Insulin works as an ____________ of the PPP

Answer 20

activator

Question 21

In the second step of the oxidative phase, the 6-phosphogluconolactone molecule is _________________________

Answer 21

hydrolyzed into 6-phosphogluconate

Question 22

Which enzyme hydrolyzes 6-phosphogluconolactone?

Answer 22

6-Phosphogluconolactone hydrolase

Question 23

Which pentose phosphate pathway enzyme catalyzes the oxidative decarboxylation of 6-phosphogluconate to form ribulose-5-phosphate?

Answer 23

6-phosphogluconate dehydrogenase.

Question 24

Which enzymes generate NADPH in the pentose phosphatepathway?

Answer 24

Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase.

Question 25

Ribulose-5-phosphate can be directly converted to which two pentose phosphate pathway metabolites?

Answer 25

Xylulose-5-phosphate (catalyed by phosphopentose epimerase) or ribose-5-phosphate (catalyzed by phosphopentoseisomerase).