Pentose Phosphate Pathway

Question 1

The pentose phosphate pathway is also known as

Answer 1

Hexo monophosphate shunt or phosphogluconate pathway

Question 2

The PPP takes place in the

Answer 2

Cytosol

Question 3

Why is the PPP referred to as a shunt?

Answer 3

It shunts the carbons back to the glycolytic pathway via its products such as fructose-6-phosphate

Question 4

State the products of the PPP used for glycolysis

Answer 4

Fructose-6-Phosphate and Glyceraldehyde-6-phosphate

Question 5

Mention the importance of the PPP.

Answer 5

It assists in lipid metabolism by providing NADPH which is used in the synthesis of fatty acids, sterols and deoxyribonucleotides.
It also provides material for the synthesis of RNA in the form of ribose-5-phosphate and the synthesis of cofactors such as FAD, NAD+/NADP+ and CoA

Question 6

The site of the minor mechanisms to generate NADPH occur in the

Answer 6

Mitochondria

Question 7

metion the important enzymes to PPP are

Answer 7

NADP-linked isocitrate dehydrogenase and NADP-linked glutamate dehydrogenase

Question 8

The NADP-linked enzymes are all

Answer 8

Cytosolic enzymes

Question 9

Mention the tissue in which PPP is active and state its role.

Answer 9

Adrenal gland (for steroid synthesis)
Liver ( Fatty acid synthesis and cholesterol synthesis)
Gonads ( sex hormone synthesis)
Adipose tissue ( Fatty Acid synthesis)
Mammary gland( FA synthesis )
RBCs ( reduction of glutathione)

Question 10

The PPP is divided into

Answer 10

2 phases

Question 11

Mentions the phases of the monophosphate shunt

Answer 11

Oxidative phase and non-oxidative phase

Question 12

Mention regulatory step of the oxidative phase of the PPP.

Answer 12

The conversion of G6P to 6PGL by G6PD

Question 13

During the oxidative phase the number of energy giving molecules formed is

Answer 13

2

Question 14

The products of the oxidative phase of PPP are

Answer 14

2NADPH + 2H+ + R5P

Question 15

For each statement state whether true or False using(T or F).
1. The reactions of the non-oxidative phase of the PPP are readily reversible.
2. The non- oxidative phase of PPP can be used to regulate glycolysis or gluconeogenesis by providing F6P and G3P depending on metabolic needs of the cell or tissue.
3. The formation of R5P and X5P by the enzymes R5P isomarase and R5P epimerase are the beginning of tge non-oxidative phase
4. Non-oxidative phase occurs when the need for energy is more than that of nitrogenous compounds

Answer 15

1. T
2. T
3. T
4. T

Question 16

When a cell needs more R5P than NADPH what happens.

Answer 16

The oxidative phase is favoured, non-oxidative phase is inhibited, the G3P from glycolysis is shunted to the PPP. Hence the PPP is favoured

Question 17

When there is balanced need for NADPH and R5P

Answer 17

only oxidative pathway is favoured

Question 18

When NADPH is more needed that R5P

Answer 18

Both phases occur
This promoted ATP formation

Question 19

PPP is regulated by

Answer 19

G6PD