Glycogen Metabolism

Question 1

How is glucose stored

Answer 1

Glycogen

Question 2

what links elongate glycogen

Answer 2

∂ 1-4 glycosidic bonds

Question 3

what links allow glycogen branching

Answer 3

∂1-6 glycosidic bond

Question 4

where is glycogen stored

Answer 4

the muscle and the liver mostly

Question 5

what is glycogen made of

Answer 5

• blood glucose
• recycling glucogenic metabolites (AAs or lactate)

Question 6

what is a glycogen granule

Answer 6

-glycogenin protein dimer core
- glycosylated with many branched chains of glycogen

Question 7

what enzyme breaks down glycogen

Answer 7

glycogen phosphorylase

Question 8

what is the glycogen phosphorylase mechanism

Answer 8

• at the non reducing end a phosphate acts as a nucleophile to break the glycosidic bond
• only breaks the ∂1-4 bond

this releases a glucose 1-Phosphate

Question 9

which carbon is the non reducing end?

Answer 9

C4

Question 10

why does glycogen phosphorylase use phosphorolysis instead of hydrolysis

Answer 10

to maintain a portion of the energy

Question 11

at a branch point where does the phosphorylase stop

Answer 11

4 glucose residues away

Question 12

how does a branched chain of glycogen break down

Answer 12

the de-branching enzyme
- brings 3 glc to the non reducing end, which. then cleaves the last ∂1-6 linkage to release a free glucose (no phosphate)

Question 13

de-branching enzyme vs glycogen phosphorylase differences

Answer 13

• glycogen phosphorylase releases glucose 1-P by breaking the ∂1-4 bonds
• de-branching enzyme releases glucose when cleaving the ∂1-6 bond

Question 14

how is glucose 1-P into glucose 6-P

Answer 14

phosphogluconomustase

Question 15

what makes phosphogluconomutase special?

Answer 15

the phosphorylated serine residue

Question 16

what enzyme works similar to phosphogluconomutase

Answer 16

phosphoglycerate mutase from glycolysis