IB Biology: C2.1 Action of epinephrine receptors

Why is epinephrine unable to cross the plasma membrane of target cells?

• It is a large molecule.

• It is water-soluble.

• It is lipid-soluble.

• It is an ion.

What happens to the G protein when epinephrine binds to its receptor on the liver cell?

• It enters the cell.

• It becomes inactive.

• One of its subunits dissociates and is activated by GTP.

• It directly activates adenylyl cyclase.

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What molecule is formed from ATP by adenylyl cyclase after it is activated by the G protein subunit?

• Glucose

• Glycogen

• cAMP

• Phosphorylase

What is the ultimate effect of epinephrine binding to liver cells during the fight-or-flight response?

• Glycogen is stored in the liver.

• Glucose is secreted into the blood.

• Protein kinase A is deactivated.

• Phosphorylase is inhibited.