Week 10

Question 1

Location of PPP

Answer 1

Cytosol of all cells; most active in liver, adipose tissue, adrenal cortex, RBCs.

Question 2

Purpose of PPP

Answer 2

Produce NADPH, make ribose-5-phosphate, and generate glycolytic intermediates.

Question 3

Rate-limiting enzyme of PPP

Answer 3

G6PD (glucose-6-phosphate dehydrogenase).

Question 4

Regulation of G6PD

Answer 4

Activated by NADP⁺; inhibited by NADPH (feedback inhibition).

Question 5

What is NADPH?

Answer 5

A reducing agent used in biosynthetic reactions and antioxidant defence.

Question 6

Uses of NADPH

Answer 6

Fatty acid synthesis, cholesterol/steroid synthesis, glutathione regeneration, cytochrome P450, respiratory burst in neutrophils.

Question 7

NADPH vs NADH

Answer 7

NADPH = anabolic + antioxidant; NADH = catabolic + ATP production.

Question 8

Tissues requiring most NADPH

Answer 8

Liver, adipose, adrenal cortex, gonads, mammary glands, RBCs, neutrophils.

Question 9

Redox (oxidative) phase of PPP

Answer 9

Irreversible phase producing NADPH, CO₂, ribulose-5-phosphate.

Question 10

Products of oxidative phase

Answer 10

2 NADPH + CO₂ + ribulose-5-phosphate.

Question 11

Function of transketolase

Answer 11

Transfers 2-carbon units; requires TPP; links pentose sugars with glycolysis.

Question 12

Function of transaldolase

Answer 12

Transfers 3-carbon units; forms fructose-6-P and glyceraldehyde-3-P.

Question 13

Purpose of non-oxidative (reversible) phase

Answer 13

Convert pentoses ↔ glycolytic intermediates depending on metabolic needs.

Question 14

What is glutathione (GSH)?

Answer 14

Tripeptide (Glu-Cys-Gly) acting as a major cellular antioxidant.

Question 15

Glutathione’s antioxidant role

Answer 15

Neutralizes H₂O₂/free radicals via glutathione peroxidase; regenerated by NADPH.

Question 16

Inheritance of G6PD deficiency

Answer 16

X-linked recessive.

Question 17

Triggers of hemolysis in G6PD deficiency

Answer 17

Oxidative stress: fava beans, infections, sulfonamides, antimalarials, nitrofurantoin, naphthalene.

Question 18

Symptoms of G6PD deficiency

Answer 18

Jaundice, dark urine, fatigue, pallor, back pain, Heinz bodies & bite cells.

Question 19

Treatment/prevention of G6PD deficiency

Answer 19

Avoid triggers, treat infections quickly, supportive care, transfusions if severe.