Glycogen Metabolism

Question 0

UDP-glucose synthesis from ___ and UTP

Answer 0

Glucose 1-phosphate! It is isomerized from glucose 6-phosphate via Phosphoglucomutase

Question 1

False about glycogenesis
A)From molecules of α-D-glucose
B)Site: cytosol of liver and muscles
C)Stimulated by high amount of glucagon
D)Energy sources: ATP and UTP

Answer 1

C)Stimulated by high amount of glucagon

Insulin dapat

Question 2

UDP-glucose pyrophosphorylase, the enzyme that forms UDP-glucose, facilitates an irreversible reaction. True or false?

Answer 2

True. Synthesis of UDP-glucose is irreversible

Question 3

This molecule, in absence of glycogen fragment…
Can accept glucose from UDP-glucose
Catalyzes the first few attachments itself
Site: Hydroxyl side-chain of a specific tyrosine

What is the molecule?

Answer 3

Glycogenin

Question 4

Why is a primer needed for glycogen synthase to start?

Answer 4

It cannot bind free glucose to UDP-glucose

Question 5

Glycogen synthase makes \_\_\_\_\_ bonds
from the terminal end which receives glucose from UDP-glucose
A)alpha (1-->6)
B)alpha (1-->4)
C)alpha (6-->1)
D)alpha (4-->1)

Answer 5

B)alpha (1–>4)

Question 6

What does nucleoside diphosphate kinase do?

Answer 6

Released UDP is phosphorylated to form UTP

Question 7

[branch forming @ glycogen]

5-8 glucosyl residues are transferred from non-reducing end & are attached to another one in chain via ___

Answer 7

Alpha(1–>6) linkage

Question 8

Primary product in glycogenolysis

Answer 8

Glucose 1-phosphate

Question 9

What enzyme produces the primary product in glycogenolysis?

Answer 9

Glycogen phosphorylase

Question 10

Glycogen phosphorylase requires ___ as coenzyme

Answer 10

Pyridoxal phosphate

Question 11

End product of glycogen phosphorylase action

Answer 11

Limit dextrin

Question 12

Removes the outer three of the four glucosyl residues attached at a branch, and transfers them to the non-reducing end of another chain

Answer 12

Glucosyl (4:4) transferase

Question 13

Conversion of Glucose 1-phosphate to Glucose 6-phosphate c/o ___

Answer 13

Phosphoglucomutase

Question 14

• A small amount of glycogen is continuously degraded by α (1–>4) glucosidase (acid maltase)
• Purpose of pathway is unknown

In what organelle does this occur?

Answer 14

Lysosome

Question 15

Glycogen synthase is Allosterically (activated, inhibited) by glucose 6-phosphate

Answer 15

Activated

Question 16

All activate glycogen phosphorylase except
A)ATP
B)glucose
C)AMP

Answer 16

C)AMP

Question 17

Binding of any of the following EXCEPT ___ signals glycogen degradation to elevate blood glucose levels or to provide energy for exercising muscles
A)glucagon
B)insulin
C)epinephrine

Answer 17

B)insulin

Question 18

•Insulin promotes overall increase in glycogen synthesis and decrease in degradation by increasing activity of what enzyme?

Answer 18

Protein phosphatase