Nitric oxide is a signal molecule that can
A) bind to surface receptors and activate second messengers.
B) bind to surface receptors and open ion channels.
C) diffuse across cell membranes and bind to receptors that regulate transcription.
D) diffuse across cell membranes and directly alter the activity of intracellular enzymes.

Question

Quizplus · Accepted Answer

Nitric oxide is a small, gaseous molecule that can diffuse across cell membranes and directly alter the activity of intracellular enzymes, such as guanylate cyclase, without the need for surface receptors.

Nitric Oxide Is a Signal Molecule That Can