PENTOSE PHOSPHATE PATHWAY

Question 1

What is the primary function of PPP?

Answer 1

Generates NADPH and ribose from glucose-6-phosphate.

Question 2

What are the two stages of PPP?

Answer 2

A: Oxidative phase and non-oxidative phase.

Question 3

Key enzyme in the oxidative phase?

Answer 3

Glucose-6-phosphate dehydrogenase

Question 4

Substrate for glucose-6-phosphate dehydrogenase?

Answer 4

Glucose-6-phosphate

Question 5

Product of the oxidative phase?

Answer 5

NADPH

Question 6

Byproduct of the oxidative phase?

Answer 6

CO2.

Question 6

Function of the non-oxidative phase?

Answer 6

Interconverts sugars

Question 7

Key enzyme in the non-oxidative phase?

Answer 7

Ribulose-5-phosphate epimerase.

Question 8

Generation of glucose from non-carbohydrate sources.

Answer 8

gluconeogenesis

Question 9

Alternative name for PPP

Answer 9

hexose monophosphate shunt

Question 10

Why is NADPH important?

Answer 10

Essential for fatty acid synthesis, cholesterol synthesis, and antioxidant defenses.

Question 11

Implication of altered PPP activity in cancer cells

Answer 11

Increased NADPH production for biosynthesis

Question 12

How is the polyol pathway implicated in diabetes complications?

Answer 12

Converts glucose to fructose, contributing to diabetic neuropathy and cataract formation.

Question 13

Product of glucose-6-phosphate dehydrogenase?

Answer 13

6-phosphogluconolactone

Question 14

Enzyme that converts 6-phosphogluconolactone to 6-phosphogluconate?

Answer 14

6-phosphogluconolactonase

Question 15

Cofactor for glucose-6-phosphate dehydrogenase?

Answer 15

NADP+.

Question 16

How is glucose-6-phosphate dehydrogenase regulated?

Answer 16

Feedback inhibition by NADPH.

Question 17

Catalyzes the conversion of glucose-6-phosphate to 6-phosphogluconolactone

Answer 17

glucose-6-phosphate dehydrogenase

Question 18

Catalyzes the conversion of 6-phosphogluconate to ribulose-5-phosphate

Answer 18

6-phosphogluconate dehydrogenase

Question 19

cofactor for 6-phosphogluconate dehydrogenase

Answer 19

NADP+

Question 20

How is 6-phosphogluconate dehydrogenase regulated?

Answer 20

Feedback inhibition by NADPH

Question 21

Glucuronic acid is synthesized from glucose via this pathway

Answer 21

Uronic acid pathway

Question 22

Deficiency in the pathway of uronic acid leads to the condition of

Answer 22

essential pentosuria

Question 23

Deficiencies in the enzymes of fructose and galactose metabolism lead to metabolic disease such as:

Answer 23

essential fructosuria, hereditary fructose intolerance, galactosemia

Question 24

Two phases of PPP reactions

Answer 24

Irreversible oxidative phase
Reversible nonoxidative phase

Question 25

A precursor of proteoglycans & conjugated glucuronides. A product of the Uronic Acid Pathway

Answer 25

Glucuronate

Question 26

It is needed for the synthesis of Lactose, Glycolipids, Proteoglycans, & Glycoproteins

Answer 26

Galactose

Question 27

catalyzes the phosphorylation of galactose using ATP as phosphate donor

Answer 27

Galactokinase

Question 28

Precursor of Amino Sugars (Hexosamines)

Answer 28

Glucose

Question 29

Major amino sugars are

Answer 29

glucosamine, galactosamine, mannosamine, sialic acid

Question 30

Principal sialic acid found in human tissues

Answer 30

N-acetylneuraminic acid

Question 31

Both fructose and sorbitol are found in the lens of the eye and may be involved in the pathogenesis of

Answer 31

Diabetic cataract

Question 32

responsible for fructose formation from glucose

Answer 32

Sorbitol “polyol” pathway

Question 33

Enzyme that catalyze the reduction of glucose to sorbitol

Answer 33

Aldose reductase