Carbohydrate Metabolism: MCQ on Glycogen Synthesis and Breakdown

1) Which of the following is false about glycogen molecules?
a) Glycogen is polysaccharide
b) Glycogen is a polymer of beta-D-Glucose
c) Glycogen consists of α(1-4) and α (1-6) glycosidic linkage
d) Glycogen have are a helical structure with branching.

2) Which of the following organs does not have glycogen storage?
a) Liver
b) Muscle
c) Intestine
d) Erythrocytes

3) Which of the following enzyme is responsible for glycogen breakdown?
a) Glycogen phosphorylase
b) Glycogen phosphatase
c) Glycogen hydrolase
d) Glycogen phosphoglycosidase

4) Liver glycogen contributes to the maintenance of glucose but not muscle glycogen. Which of the following enzyme is absent in muscle?
a) Glycogen phosphorylase
b) Hexokinase
c) Glucose-6-phosphatase
d) Debranching enzyme

5) Which of the enzyme is responsible for the hydrolysis of α (1-6) glycosidic bond present at a branching point of glycogen molecules?
a) β-Glucosidase
b) α- Glucosidase
c) Glycosidase
d) Phosphorylase

6) Glycogen phosphorylase is responsible for the breakdown of glycogen to
a) Glucose
b) Glucose-1-phosphate
c) Glucose-6-phosphate
d) Maltose

7) Which of the following is false about enzyme glycogen phosphorylase of glycogen breakdown?
a) Glycogen phosphorylase is active as a homodimer.
b) Glycogen phosphorylase is present in two conformation state
c) Glycogen phosphorylase possess high-affinity binding to glycogen in T conformational state
d) Glycogen phosphorylase high-affinity binding to glycogen in R conformation state

8) Which of the following metabolite allosterically activate glycogen phosphorylase?
a) ATP
b) AMP
b) Glucose-6-P
d) Glucose-1-P

9) In response to glucagon and epinephrine, cells undergo a series of changes in signal-transducing molecules that phosphorylates and activates glycogen phosphorylase. Which of the following enzyme is responsible for covalent modification of glycogen phosphorylase?
a) Protein kinase A
b) Phosphorylase kinase
c) Protein kinase C
d) Protein kinase B

10) Which of the following is not the direct/ indirect activator of glycogen phosphorylase in muscle?
a) AMP
b) Ca++
c) Epinephrine
d) Insulin

11) Which of the following protein is required for de novo synthesis of glycogen?
a) Glycoprotein
b) Glycogenin
c) Proteoglycan
d) Glucogenin

12) Which of the following enzyme is responsible for the addition of UDP-Glucose to the existing chain?
a) Glycogen synthase
b) Glycogen polymerase
c) Glycogen synthetase
d) Glyocogen lyase

13) All the following enzymes are involved in glycogen synthesis except
a) Hexokinase
b) Phosphoglucomutase
c) Glucose-1-P uridylyltransferase
d) Glycogen synthetase

14) Which of the following statement is false regarding glycogenesis?
a) Glycogen synthase is activated in the phosphorylated state.
b) Glycogen synthase enzyme is inhibited by glucagon and epinephrine action.
c) Protein phosphatase removes the phosphate group and activates the enzyme
d) Insulin promotes glycogen synthesis in liver and skeletal muscles

15) The iodine test is used to differentiate glycogen from starch. On iodine test glycogen gives
a) Blue color
b) Green color
c) Yellow color
d) Violet color

Answers:
1-b, 2-d, 3-a, 4-c, 5-b, 6-c, 7-c, 8-b, 9-b, 10-d
11-b, 12-a, 13-d, 14-a, 15-d