MCP - Cross - 2/9 - Glycolysis and Glycogen

Question 1

Which enzyme catalyzes the cleavage of fructose-1,6-bisphosphate (FBP) into dihydroxyacetone (DHAP) and glyceraldehyde-3-phosphate (GAP)?
A. Epimerase B. Enolase
C. Isomerase D. Mutase
E. Aldolase

Answer 1

E. Aldolase

Question 2

The enzyme phosphoglucomutase plays a direct role in which metabolic pathway?

Answer 2

Glycogen synthesis

Question 3

Which of the following enzymes catalyzes the conversion of glucose-6-phosphate (G6P) to fructose-6-phosphate (F6P)?

1. Aldolase 2. Enolase
2. Epimerase 4. Isomerase
3. Mutase

Answer 3

4. Isomerase

Question 4

Which of the following enzymes has a phosphotidyl intermediate?
A. Enolase     B. Glycogen sunthase
C. Lactate Dehydrogenase     
D. Phosphoglycerate Mutase
E. Phosphomannose Isomerase

Answer 4

D. Phosphoglycerate Mutase

Question 5

The immediate degradation of glycogen under normal conditions gives rise to which one of the following?
A. More glucose than glucose-1-phosphate (G1P)
B. More G1P than glucose
C. Equal amounts of glucose and G1P
D. Neither glucose nor G1P
E. Only G1P

Answer 5

B. More G1P than glucose
From the alpha 1,4, you get G1Ps (phosphorylase) and from the alpha 1,6, you get glucoses (debranching enzyme)
10:1 ratio of G1P to glucose

Question 6

In an embryo with a complete deficiency of pyruvate kinase, how many net moles of ATP are generated in the conversion of 1 mole of glucose to 1 mole of pyruvate?
A. 0
B. 1
C. 2
D. 3

Answer 6

A. 0
Spend 2 (1st 5 steps), gain 2 instead of 4 (2nd 5 steps)

Question 7

Which one of the following is a regulatory mechanism employed by muscle for glycolysis?
A. Inhibition of PFK1 by AMP
B. Inhibition of hexokinase by its product
C. Activation of pyruvate kinase when glucagon levels are elevated
D. Inhibition of aldolase by FBP

Answer 7

B. Inhibition of hexokinase by its product

Hexokinase is inhibited by G6P

Question 8

Which of the following metabolites is used by all cells for glycolysis, glycogen synthesis, and the hexose monophosphate shunt pathway?
A. G1P
B. G6P
C. UDP-glucose
D. F6P
E. Phosphoenolpyruvate

Answer 8

B. G6P is common to all pathways.

Question 9

What are the clinical features of Von Gierke disease?

Answer 9

Von Gierke disease is a glycogen storage disease that affects the liver and kidneys. The defective enzyme is glucose-6-phosphatase or its transport system, resulting in increased amounts of glycogen, however the structure of glycogen is normal. The clinical features are: massive enlargement of the liver, failure to thrive, severe hypoglycemia, ketosis, hyperuricemia, hyperlipemia

Question 10

What is this disease? A progressive disease from defective branching enzyme that makes alpha 1-4 bonds alpha 1-6.

Answer 10

Anderson Disease
The amount of glycogen is normal, but the structure is largely unbranched, the branches that exist are very long. This is a progressive disease, resulting in cirrhosis of the liver and liver failure, and death, usually by age 2.

Question 11

What disease results from defective phosphorylase enzyme in the glycogen storage and breakdown pathway? What organ is affected and how?

Answer 11

This is McArdle Disease, and the main source of problems is the muscles. The structure of glycogen is normal, but there are increased amounts of it. Limited ability to perform strenuous exercise because of painful muscle cramps. Otherwise, patients are normal and well-developed.