Glycogen Metabolism: Old Test Questions

Front 1

In glycogen, the chains are formed by ____ glycosidic linkages while the branches are ____ glycosidic linkages.

Back 1

alpha-1,4/alpha-1,6

Front 2

The key regulatory enzyme in glycogen breakdown is ____.

Back 2

Phosphorylase

Front 3

The key regulatory enzyme in glycogen synthesis is ____.

Back 3

Glycogen Synthase

Front 4

The formation of primers to initiate glycogen synthesis is carried out by ___.

Back 4

Glycogenin

Front 5

This hormone leads to glycogen synthesis.

Back 5

Insulin

Front 6

Phosphorylase b is converted to phosphorylase a by ____.

Back 6

Phosphorylase Kinase

Front 7

The active form of glycogen synthase is ___.

Back 7

Dephosphorylated.

Front 8

The active form of glucose used in glycogen synthesis is ____.

Back 8

UDP Glucose

Front 9

The enzyme which removes the glucose residue at branch points of glycogen during glycogen breakdown is ____.

Back 9

Debranching Enzyme

Front 10

Phosphorylase kinase is regulated by ____.

Back 10

Calcium Ions and cAMP activated PKA

Front 11

Debranching enzyme produces ____.

Back 11

Glucose

Front 12

Phosphorylase a in the liver is allosterically regulated by ____.

Back 12

Glucose

Front 13

When protein phosphatase 1 is active,

a.) glycogen synthesis predominates
b.) glycogen breakdown predominates
c.) neither
d.) both

Back 13

Glycogen synthesis predominates.

This is because PP1 dephosphorylates phosphorylase a converting it to the inactive form phosphorylase b, resulting in no degradation.

Front 14

The key enzyme in glycogen degradation is ___.

Back 14

Phosphorylase

Front 15

What molecule must be excluded from the active site of glycogen phosphorylase?

Back 15

Water

Front 16

What is the function of liver glycogen degradation?

Back 16

For glucose export to other tissues when glucose levels are low.

Front 17

The two hormones that signal for glycogen breakdown are ____ and ____.

Back 17

Epinephrine and Glucagon

Front 18

The enzyme that removes the phosphate from glycogen synthase, converting it to the active a form is ____.

Back 18

Protein Phosphatase 1

Front 19

Why is glycogen branching important?

Back 19

1.) Increases solubility
2.) More terminals = faster breakdown/synthesis

Front 20

The efficiency of glycogen storage in terms of energy cost is about __%

Back 20

97%

Front 21

The major non-hormonal signal used by the liver to signal the need for glycogen synthesis is ____.

Back 21

The blood glucose concentration.