1.12 Glycogen Metabolism Flashcards Preview

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Flashcards in 1.12 Glycogen Metabolism Deck (22)
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0
Q

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

A

the nonreducing end of a glycogen chain

1
Q

Where is Glycogen mostly stored

A

In liver and muscle

2
Q

What enzyme degrades the terminal glucose from the glycogen chain

A

Glycogen Phosphorylase

3
Q

Glycogen metabolism is demonstrative of a hydrolysis or a phosphorolysis?

A

Phosphorolysis

4
Q

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

A

On the fourth residue from the branch point

5
Q

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

A

Glucose 1-Phosphate

6
Q

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

A

Phosphoglucomutase

7
Q

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

A

The activation and attachment of a sugar nucleotide

Ex: G1P + UTP –> UDP-Glucose

8
Q

What enzyme catalyzes the addition of a sugar nucleotide to G1P

A

UDP-glucose pyrophosphorylase

9
Q

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

A

Phosphoglucomutase

10
Q

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

A

Glycogen Synthase

11
Q

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

A

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

12
Q

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

A

True

13
Q

How is a branch made during Glycogen synthesis

A

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

14
Q

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

A

branching enzyme Glycosyl (4-6) transferase

15
Q

Role of Glycogenin

A

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

16
Q

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

A

Phosphoglucomutase

17
Q

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

A

True

18
Q

Glycogen Phosphorylase is phosphorylated to form a, what occurs?

A

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

19
Q

Phosphorylase a is dephosphorylated or phosphorylated?

A

Phosphorylated

20
Q

Glycogen Synthase a is dephosphorylated or phosphorylated?

A

Dephosphorylated

21
Q

When glycogen synthase a is dephosphorylated, what is triggered?

A

Glycogen Synthesis