Week 10

Question 1

Pentose Phosphate Pathway (PPP)

Answer 1

Hexose Monophosphate (HMP) shunt

Question 2

Where does the PPP occur?

Answer 2

Cytosol

Question 3

What are the two main products of PPP?

Answer 3

NADPH and Ribose-5-phosphate

Question 4

Does PPP produce ATP?

Answer 4

No

Question 5

What is the relationship between PPP and glycolysis?

Answer 5

They share intermediates (G6P, F6P, G3P)

Question 6

Which glycolytic intermediate enters PPP?

Answer 6

Glucose-6-phosphate

Question 7

In which state is PPP flux increased?

Answer 7

Well-fed state (insulin upregulates G6PD)

Question 8

What is the rate-limiting enzyme of PPP?

Answer 8

Glucose-6-phosphate dehydrogenase (G6PD)

Question 9

What does G6PD produce?

Answer 9

NADPH

Question 10

How many NADPH molecules are produced per G6P in oxidative phase?

Answer 10

2 NADPH

Question 11

What carbon is released as CO₂?

Answer 11

Carbon 1 of glucose

Question 12

What stimulates G6PD?

Answer 12

NADP⁺ (low NADPH levels)

Question 13

What inhibits G6PD?

Answer 13

NADPH (feedback inhibition)

Question 14

What type of reaction is 6-phosphogluconate dehydrogenase?

Answer 14

Oxidative decarboxylation

Question 15

What is NADPH mainly used for?

Answer 15

Anabolic (reductive biosynthetic) reactions

Question 16

Examples of NADPH use?

Answer 16

Fatty acid synthesis
Steroid synthesis
Maintaining reduced glutathione
Respiratory burst

Question 17

What is NADH mainly used for?

Answer 17

ATP production in ETC

Question 18

Is NADPH reoxidized by the respiratory chain?

Answer 18

No

Question 19

Why are NADPH and NADH kept separate?

Answer 19

To separate anabolic and catabolic pathways.

Question 20

Is the non-oxidative phase reversible?

Answer 20

Yes

Question 21

What is the main purpose of the non-oxidative phase?

Answer 21

Interconversion of sugars (3C–7C)

Question 22

What enzyme converts ribulose-5-P → ribose-5-P?

Answer 22

Isomerase

Question 23

What enzyme interconverts ribulose-5-P and xylulose-5-P?

Answer 23

Epimerase

Question 24

What enzyme transfers 2-carbon units?

Answer 24

Transketolase

Question 25

What cofactor does transketolase require?

Answer 25

TPP (Vitamin B1) + Mg²⁺

Question 26

What enzyme transfers 3-carbon units?

Answer 26

Transaldolase

Question 27

In RBCs, where are pentoses routed?

Answer 27

Back to glycolysis (F6P & G3P)

Question 28

In rapidly dividing cells, ribose-5-P is used for:

Answer 28

Nucleotide synthesis

Question 29

What is the major antioxidant molecule in RBCs?

Answer 29

Reduced glutathione (GSH)

Question 30

What enzyme uses NADPH to regenerate glutathione?

Answer 30

Glutathione reductase

Question 31

What enzyme uses GSH to detoxify peroxides?

Answer 31

Glutathione peroxidase (selenium-dependent)

Question 32

What happens when glutathione is oxidized?

Answer 32

Forms GSSG (inactive form)

Question 33

Why is NADPH essential in RBCs?

Answer 33

Maintains glutathione in reduced form

Question 34

What happens to hemoglobin when oxidized?

Answer 34

Forms Heinz bodies

Question 35

What are bite cells?

Answer 35

RBCs after splenic macrophages remove Heinz bodies

Question 36

What enzyme complex generates ROS in neutrophils?

Answer 36

NADPH oxidase

Question 37

What molecule does NADPH oxidase use?

Answer 37

O₂

Question 38

Role of ROS in immune response?

Answer 38

Kill pathogens

Question 39

Inheritance pattern of G6PD deficiency?

Answer 39

X-linked recessive

Question 40

Which population is most affected?

Answer 40

Males

Question 41

Geographic prevalence?

Answer 41

Africa, Mediterranean, Middle East, Asia

Question 42

Why is it protective?

Answer 42

Resistance to falciparum malaria

Question 43

What triggers hemolysis?

Answer 43

Oxidative stress Examples: * Infections * Fava beans (favism) * Oxidant drugs (AAA)

Question 44

AAA mnemonic stands for?

Answer 44

Antibiotics Antimalarials Antipyretics

Question 45

What happens in G6PD deficiency at molecular level?

Answer 45

↓ NADPH → ↓ reduced glutathione → ↑ oxidative damage

Question 46

Why are RBCs especially affected?

Answer 46

No alternative NADPH source (no mitochondria)

Question 47

Clinical manifestation?

Answer 47

Hemolytic anemia

Question 48

What happens to RBC membrane?

Answer 48

Oxidation → rigidity → splenic destruction

Question 49

Does PPP produce CO₂?

Answer 49

Yes

Question 50

Does glycolysis produce CO₂?

Answer 50

No

Question 51

Which pathway produces ATP?

Answer 51

Glycolysis

Question 52

Which pathway produces NADPH?

Answer 52

PPP

Question 53

When does PPP operate to maximize NADPH?

Answer 53

When ribose not needed, high NADP⁺ levels.

Question 54

When does PPP operate to maximize ribose-5-P?

Answer 54

In rapidly dividing cells.

Question 55

How does xylulose-5-P affect glycolysis?

Answer 55

Increases F2,6BP → stimulates PFK-1 → ↑ glycolysis