Some hormones can not enter a cell directly because they are too large or polar.From the list select the molecule that acts as a secondary messenger for some of these hormones that can not enter a cell directly.
A)catecholamine
B)cyclic AMP
C)epinephrine
D)norepinephrine
E)calcitonin

Question

Quizplus · Accepted Answer

Cyclic AMP (cAMP) acts as a secondary messenger for some hormones that cannot enter a cell directly because they are too large or polar. Hormones such as epinephrine and norepinephrine bind to membrane receptors on the cell surface, which activate the G protein signaling pathway, leading to the production of cAMP within the cell. Cyclic AMP then activates protein kinases, which phosphorylate target proteins and mediate the cellular response to the hormone signal.

Some Hormones Can Not Enter a Cell Directly Because They