$$\text{UDP-glucose} + (\text{Glucose})_n \rightarrow (\text{Glucose})_{n+1} + \text{UDP}$$

Question 1

Which type of glycosidic linkage is primarily found in the main chain of glycogen?

Accepted Answer

$$\alpha(1 \rightarrow 4)$$

Question 2

What is the typical number of glucose subunits between branch points in glycogen?

Accepted Answer

10-14 subunits

Question 3

Which enzyme catalyzes the synthesis of glycogen from UDP-glucose?

Accepted Answer

Glycogen synthase

Question 4

What is the immediate product released when UDP-glucose is added to a growing glycogen chain?

Accepted Answer

UDP

Question 5

Which protein acts as the primer for glycogen synthesis by providing the first glucose residues?

Accepted Answer

Glycogenin

Question 6

What is the role of the branching enzyme in glycogen synthesis?

Accepted Answer

It transfers 6-10 subunits to create $$\alpha(1 \rightarrow 6)$$ branches.

Question 7

Which of the following best describes the function of UDP-glucose in glycogen synthesis?

Accepted Answer

It serves as the glucose donor for glycogen elongation.

Question 8

Which step in glycogen synthesis requires the hydrolysis of pyrophosphate ($$PP_i$$)?

Accepted Answer

Conversion of glucose-1-phosphate to UDP-glucose

Question 9

A patient with a deficiency in branching enzyme would most likely have glycogen with which characteristic?

Accepted Answer

Long, unbranched chains

Question 10

Which of the following reactions is catalyzed by glycogen synthase?

Accepted Answer

$$	ext{UDP-glucose} + (	ext{Glucose})_n ightarrow (	ext{Glucose})_{n+1} + 	ext{UDP}$$

Question 11

Why is branching important in glycogen structure?

Accepted Answer

It increases the solubility and allows rapid release of glucose.

Question 12

Which of the following best explains why glycogenin is essential for glycogen synthesis?

Accepted Answer

It initiates the synthesis by autoglucosylation, providing a primer for glycogen synthase.

Question 13

If a mutation prevents the release of UDP during glycogen synthesis, what would be the most direct consequence?

Accepted Answer

Glycogen chains would not elongate.

Question 14

Which of the following is the correct sequence of events in glycogen synthesis?

Accepted Answer

Glucose $$\rightarrow$$ Glucose-6-phosphate $$\rightarrow$$ Glucose-1-phosphate $$\rightarrow$$ UDP-glucose $$\rightarrow$$ Glycogen

Question 15

A defect in which enzyme would most directly impair the formation of $$\alpha(1 \rightarrow 6)$$ branches in glycogen?

Accepted Answer

Branching enzyme

Glycogen Metabolism: Structure and Synthesis

Guida di studio - Domande di pratica