Pentose Phosphate Pathway

Question 1

The pentose phosphate pathway produces NADPH. What three functions does it serve?

Answer 1

1) required for fatty acid synthesis in the liver, adipose tissue, and lactating mammary glands
2) required for synthesis of cholesterol and steroid hormones in liver, adrenal glands, and gonads
3) regenerates reduced glutathione to counter damage from oxygen radicals in all cells

Question 2

The pentose phosphate pathway produces ribose 5-phosphate. What two functions does it serve?

Answer 2

1) required to make DNA, RNA, NADH, FADH2, and coenzyme A

2) used in rapidly dividing cells (bone marrow, skin, intestinal mucosa, and tumors)

Question 3

Key regulatory enzyme and first step of oxidative pentose phosphate pathway

Answer 3

Glucose 6-phosphate dehydrogenase (G6PD)

Question 4

Inhibitor of glucose 6-phosphate dehydrogenase (G6PD)

Answer 4

NAPDH. When NADPH is consumed in biosynthetic pathways and reduction of glutathione, the enzyme becomes more active

Question 5

Summary of the nonoxidative pentose phosphate pathway

Answer 5

Converts six 5-carbon sugar phosphates to five 6-carbon sugar phosphates

Question 6

Caused by a severe thiamine deficiency. Chronic, heavy alcohol consumption interferes with intestinal absorption of thiamine. Symptoms include: memory loss, inability to make new memories, mental confusion, vision issues, and partial paralysis.

Answer 6

Wenicke-Korsakoff syndrome

Question 7

Individuals are more sensitive to a thiamine deficiency due to a gene mutation for this enzyme in nonoxidative pentose phosphate pathway

Answer 7

Transketolase. The mutation lowers affinity of enzyme for TPP

Question 8

Which intermediate from the nonoxidative pentose phosphate pathway can enter either the glycolitic or gluconeogenic pathway?

Answer 8

Glyceraldehyde 3-phosphate

Question 9

Function of glutathione

Answer 9

protects cells against reactive oxygen species

Question 10

Present in fava beans, this compound oxidizes NAPDH and glutathione. Depletion of glutathione results in inability to deal with oxidative stress.

Answer 10

Divicine

Question 11

X-linked genetic disorder. Mostly asymptomatic but begins to show symptoms oxygen radicals are generated due to stress from infection, certain drugs, herbicides, or divicine from fava beans.

Answer 11

Glucose 6-Phosphate Dehydrogenase (G6PD) deficiency

Question 12

What happens to erythrocytes in Glucose 6-Phosphate Dehydrogenase (G6PD) deficiency?

Answer 12

Membranes break down and proteins breakdown/aggregate. Erythrocytes eventually lyse, leading to hemolytic anemia.

Question 13

Without ____ to reduce glutathione (in Glucose 6-phosphate dehydrogenase deficiency), H202 and hydroxyl free radicals cause oxidative damage to lipids, proteins, and DNA

Answer 13

NADPH