1.12-Glycogen Metabolism

Question 1

Where are the two main storage places for Glycogen?

Answer 1

The liver and skeletal muscle

Question 2

How many reducing ends are there in Glycogen? Which number do we give to this carbon?

Answer 2

1 Reducing end. Carbon 1

Question 3

How many non reducing ends are there in Glycogen?

Answer 3

FREAKING TONS

Question 4

What are the straight chain linkages in Glycogen? What are the branch links?

Answer 4

Chain: 1,4 alpha Branches: 1,6 alpha

Question 5

Which end do we use to start breaking down glycogen?

Answer 5

The terminal end…the NONreducing end

Question 6

What is the enzyme that helps us break down glycogen?

Answer 6

Glycogen Phosphorylase

Question 7

Is the breakdown of glycogen hydrolysis or phosphorolysis?

Answer 7

Phosphorolysis

Question 8

After how many glucose molecules does glycogen phosphorylase cut?

Answer 8

Every 4th glucose molecule

Question 9

What is the enzyme that breaks the alpha 1,6 linkages? if you get this wrong I will hurt you..

Answer 9

Debranching Enzyme

Question 10

What does phosphorglucomutase do after a branch has been cut AND to start Glycogen synthesis?

Answer 10

Since we had a Glucose 1 Phosphate we need it changed to Glucose 6 phosphate for Glycolysis….REVERSE to start Glycogen Synthesis!!

Question 11

Is the substrate for glycogen synthesis sugar? What is the name of the substrate?

Answer 11

NO! its a sugar-nucleotide!! UDP-Glucose

Question 12

What catalyzes UDP to come off the glucose to synthesize the glycogen chain? THESE ENZYMES HAVE STRAIGHT FORWARD NAMES :)

Answer 12

Glycogen Synthase

Question 13

What enzyme is needed to make a 1,6 alpha linkage (a branch)?

Answer 13

Glycosyl (4-6) Transferase…It transfers the chunk of glucose molecules from a 4 linkage to a 6 linkage :)

Question 14

What is the name of the primer needed for Glycogen synthesis?

Answer 14

Glycogenin

Question 15

What is the only enzyme that both glycogeneis and glycogenolysis have in common?

Answer 15

Phospho-Gluco-Mutase

Question 16

How are the pathways of Glycogenesis and glycogenolysis related concerning their regulation?

Answer 16

They are reciprocally regulated. When one is going it inhibits the other.

Question 17

What are the two forms of Glycogen Phosphorylase? Which form is active? Which form is inactive?

Answer 17

A=active and B=inactive

Question 18

Here’s the Sitch: Your working out and you need more glucose. What two things does protein kinase A phosphorylate and what is the result of each?

Answer 18

Protein Kinase A phosphorylates: 1. Phosphorylase Kinase which activates phosphorylase to break glycogen. 2. Glycogen Synthase which inactivates it

Question 19

What does phosphorylation of BOTH enzymes in building/breaking down of glycogen result in?

Answer 19

Glycogen Degradation

Question 20

What does Dephosphorylation of both enzymes in breaking/building glycogen result in?

Answer 20

Glycogen Synthesis

Question 21

What is even faster then hormonal control for glycogen regulation?

Answer 21

Allosteric Regulation by AMP and Glucose

Question 22

What is the R state? T State?

Answer 22

R=Ready(Active) T=Tired (Less Active)

Question 23

What is the default state for phosphorylase in the MUSCLE? a or b? What is it activated by?

Answer 23

B (less active in muscle) Activated to R by AMP

Question 24

What is the default state for Phosphorylase in the LIVER? a or b? What is it deactivated by?

Answer 24

A Deactivated by glucose to T

Question 25

FOUNDATIONAL: Does the liver make more glycogen or break down glycogen when Glucose is introduced to the blood?

Answer 25

It starts MAKING glycogen. The liver is constantly breaking it down (Phosphorylase A) until the body doesn’t need it.

Question 26

What is the defective enzyme in Von Gierke Syndrome?

Answer 26

Glucose-6-Phosphatase does not fxn so we can’t make Glucose