Cellular Responses

Part A

The cleavage of glycogen by glycogen phosphorylase releases _____.

	glucose-1-phosphate
	galactose-1-phosphate
	nothing: glycogen phosphorylase cannot cleave glycogen
	fructose-1-phosphate
	cellulose

Correct

Glycogen is a polysaccharide composed of glucose monomers.

Part B

Epinephrine acts as a signal molecule that attaches to _____ proteins.

	G-protein-linked receptor
	nuclear receptor
	receptor tyrosine kinase
	intracellular receptor
	ion-channel receptor

Correct

Epinephrine acts via G-protein-linked receptors.

Part C

Which of these is a receptor for calcium ions?

	IP3
	calmodulin
	adenylyl cyclase
	G protein
	PIP2

Correct

Calmodulin is a calcium ion receptor.

Part D

Which of these is NOT correct?

	Tyrosine-kinase receptors consist of two polypeptides that join when activated by a signal molecule.
	Ion channels are found on both the plasma membrane and the endoplasmic reticulum.
	Phospholipase C catalyzes the formation of IP3.
	Kinases are enzymes that phosphorylate other molecules.
	Cyclic AMP binds to calmodulin.

Correct

Calcium binds to calmodulin.

Part E

A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to _____ receptors.

	G-protein-linked
	steroid
	intracellular
	ion-channel
	receptor tyrosine kinase

Correct

GTP activates G proteins.