Question

Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?a) Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP.b) Epinephrine binds to a cell-surface receptor; the activated receptor catalyzes the conversion of glycogen to glucose.c) Epinephrine diffuses through the plasma membrane; the hormone dimerizes in the cytosol.d) Epinephrine is taken into the cell by endocytosis; glycogen is converted to glucose in the endocytotic vesicle.

Answer 1

Answer: A

Explanation:

In situations of fight or flight response, the emergency need for energy initiate the break-down of glycogen to glucose. The initial step involves Epinephrine a hormone being released by the adrenal gland.

A signal is initiated when epinephrine binds to a G-protein epinephrine receptor on the surface of liver cells. The receptor molecules then stimulate an enzyme called adenylyl cyclase which converts significant amount of ATP molecules into cyclic adenosine monophosphate (cAMP). cAMP convey the initial message of epinephrine into the cell hence they are called second messengers.

Answer is A