Hexose Monophosphate Pathway

Question 1

What does the Hexose Monophosphate Pathway produce (4)

Answer 1

1. Ribose 5-phosphate: used for synthesis of DNA/RNA
2. Ribulose 5-phosphate
3. Xylulose 5-phosphate
4. NADPH

Question 2

HMP takes place in what part of the cell?

Answer 2

Cytosol

Think glycolytic intermediates

Question 3

What do liver, adipose tissues, lactating mammary glands use NADPH for?

Answer 3

Fatty acid biosynthesis

Question 4

What do the adrenal cortex, ovaries, testes, placenta use NADPH for?

Answer 4

Synthesis of steroid hormones: hydroxylation reactions

Question 5

What do erythrocytes use NADPH for?

Answer 5

Protection against oxidative disease d/t reduction of glutathione

Question 6

What do WBC and macrophages use NADPH for?

Answer 6

Killing phagocytosed bacteria

Question 7

What does the Thyroid gland use NADPH for?

Answer 7

Coenzyme for the synthesis of T3/T4

Question 8

What are the 2 phases of the HMP

Answer 8

1. Oxidative
2. Non-oxidative

Question 9

What are the key features of the oxidative phase?

(4)

Answer 9

1. Reactions are irreversible
2. Formation of NADPH and pentose phosphate, ribulose 5-phosphate
3. Enzymes are all dehydrogenases
4. Reactions catalyzed by glucose 6-phosphate dehydrogenase which is the major regulatory site for HMP

Question 10

Key features of the Non-oxidative phase

Answer 10

1. Reactions are reversible
2. Results in formation of ribose-5-phosphate for nucleic acid biosynthesis
3. Interconversion of sugars
4. Enzymes are transketolace (2C) and transaldose (3)

Question 11

What are the regulators of Glucose 6 phosphate dehydrogenase?

3

Answer 11

1. Allosterically stimulated by NADP+
2. Inhibited by NADPH
3. Activated by insulin

Question 12

What is the rate-limiting (committed) step for the HMP pathway?

Answer 12

Glucose 6-phosphate dehydrogenase

Question 13

Is ATP used in HMP?

Answer 13

NO

Question 14

The intermediate, activated forms of oxygen are known as what?

Answer 14

Reactive oxygen species (ROS)

Question 15

Reactive oxygen species-induced cellular damage

Answer 15

Damage to lipids, proteins, nucleic acids and carbohydrates-results in cell damage/death

Question 16

What are the anti-oxidant scavengers that clear reactive oxygen species?

Answer 16

ACE
Vitamin A,C,E

Question 17

NADPH & Immunity
Phagocytosis of pathogens

Answer 17

Leukocytes, macrophages, neutrophils utilize oxygen-dependent mechanisms to destroy bacteria via oxidative burst

Question 18

Glutathione reductase coenzyme

Answer 18

Reduce oxidative stress via reduction of H2O2

Question 19

NADPH oxidase coenzyme

Answer 19

immunity via phagocytosis of pathogens by WBCs

Question 20

Synthesis of Nitric Oxide

Answer 20

Generation of nitric oxide and reactive oxygen species by phagocytes

Question 21

NADPH & Oxidative stress

Answer 21

1. Prevents oxidative stress
2. Reduces glutathione via glutathione reductase
3. Glutathione peroxidase-converts H2O2 to H2O
4. Convert hydroxyl free radicals