1.12 Glycogen Metabolism

Question 0

Glycogen is degraded by removal of a terminal glucose from where?

Answer 0

the nonreducing end of a glycogen chain

Question 1

Where is Glycogen mostly stored

Answer 1

In liver and muscle

Question 2

What enzyme degrades the terminal glucose from the glycogen chain

Answer 2

Glycogen Phosphorylase

Question 3

Glycogen metabolism is demonstrative of a hydrolysis or a phosphorolysis?

Answer 3

Phosphorolysis

Question 4

At what point on the Glycogen chain does the enzyme stop removing terminal glucose molecules?

Answer 4

On the fourth residue from the branch point

Question 5

After Glucose molecule is released from Glycogen chain, what structure is it?

Answer 5

Glucose 1-Phosphate

Question 6

What enzyme converts Glucose 1-phosphate to Glucose 6-phosphate?

Answer 6

Phosphoglucomutase

Question 7

What activates and prepares Glucose 1-phosphate to be added to the glycogen chain?

Answer 7

The activation and attachment of a sugar nucleotide

Ex: G1P + UTP –> UDP-Glucose

Question 8

What enzyme catalyzes the addition of a sugar nucleotide to G1P

Answer 8

UDP-glucose pyrophosphorylase

Question 9

What enzyme catalyzes the first step of glycogen synthese by converting G6P to G1P

Answer 9

Phosphoglucomutase

Question 10

What enzyme catalyzes the addition of the glycosyl unit to the glycogen chain?

Answer 10

Glycogen Synthase

Question 11

What happens to UDP during the addition of the glycosyl unit to the terminal end of the glycogen chain

Answer 11

It is displaced by the terminal Hydroxyl group of the growing glycogen molecule

Question 12

T or F, The glycosyl residues can only be added to the glycogen chain if it already contains 4 residues

Answer 12

True

Question 13

How is a branch made during Glycogen synthesis

Answer 13

Breaking of an alpha 1-4 link of a block of about six or seven glycosyl residues from the terminal nonreducing end. This block is transfered to a more interior residue on the C-6

Question 14

What enzyme catalyzes the alpha 1-6 linkages found at branching sites

Answer 14

branching enzyme Glycosyl (4-6) transferase

Question 15

Role of Glycogenin

Answer 15

Acts as a primer for new branches of glycogen. Since glycogen synthase can only add to chains of 4 residues, this enzyme makes those first four residues attach so that glycogen synthase can act

Question 16

What is the only enzyme that is common to both glycogen synthesis and metabolism

Answer 16

Phosphoglucomutase

Question 17

T or F, Glycogen synthesis and breakdown are reciprocally regulated, stimulation of one inhibits the other

Answer 17

True

Question 18

Glycogen Phosphorylase is phosphorylated to form a, what occurs?

Answer 18

This is the active form of glycogen phosphorylase and triggers glycogen breakdown

Question 19

Phosphorylase a is dephosphorylated or phosphorylated?

Answer 19

Phosphorylated

Question 20

Glycogen Synthase a is dephosphorylated or phosphorylated?

Answer 20

Dephosphorylated

Question 21

When glycogen synthase a is dephosphorylated, what is triggered?

Answer 21

Glycogen Synthesis