Chapter 21. Glycogen Metabolism

Question 1

In vertebrates, a ubiquitous protein in vertebrates that, when bound to calcium, stimulates many enzymes and transporters.

Answer 1

Calmodulin

Question 2

The regulatory enzyme that phosphorylates and activates glycogen phosphorylase. Phosphorylase kinase is activated by phosphorylation and calcium binding.

Answer 2

Phosphorylase kinase

Question 3

the enzyme that catalyzes the phosphorolysis of glycogen to yield glucose 1-phosphate; it is an allosteric enzyme whose activity is further regulated by reversible covalent modification.

Answer 3

Glycogen phosphorylase

Question 4

a catecholamine released by the adrenal medulla in response to muscle activity or its anticipation that stimulates the breakdown of muscle glycogen..

Answer 4

Epinephrine (adrenaline)

Question 5

an allosteric enzyme that can also be reversibly covalently regulated and is responsible for the synthesis of glycogen; it transfers glucose from UDP-glucose to the hydroxyl group at a C-4 terminus of glycogen.

Answer 5

Glycogen synthase

Question 6

a polypeptide hormone that is secreted by the α cells of the pancreas when blood glucose level is low and leads to glycogen breakdown in the liver and release of glucose to the blood.

Answer 6

Glucagon

Question 7

The cleavage of a bond by orthophosphate, as in the degradation of glycogen to glucose 1-phosphate.

Answer 7

Phosphorolysis

Question 8

a polypeptide hormone secreted by the alpha-cells of the pancreas that stimulates fuel storage and protein synthesis.

Answer 8

insulin

Question 9

a protein bearing an oligosaccharide of α-1,4 glucose units which is the primer for glycogen synthase. Glycogenin catalyzes its own autoglycosylation using UDP-glucose.

Answer 9

Glycogenin

Question 10

A protein kinase that phosphorylates and thereby inhibits glycogen synthase.

Answer 10

glycogen synthase kinase

Question 11

the activated form of glucose used in the synthesis of glycogen. It is formed from glucose 1-phosphate and UTP.

Answer 11

Uridine diphosphate glucose (UDP-glucose)

Question 12

a protein kinase that consists of two catalytic subunits and two regulatory subunits, which inhibit the catalytic subunits. Upon binding of cAMP, the regulatory subunits dissociate from the catalytic subunits, which then become active.

Answer 12

Protein kinase A (PKA)

Question 13

prosthetic group derived from vitamin B6(pyridoxine) that plays a key role in transamination reactions.

Answer 13

Pyridoxal phosphate (PLP)

Question 14

a protein phosphatase stimulated by insulin that inhibits glycogen degradation and stimulates glycogen synthesis.

Answer 14

Protein phosphatase 1 (PP1)