The two major categories of extracellular signaling molecules that bind to cell surface receptors are ____.
A) peptide hormones and steroid hormones
B) steroid hormones and neurotransmitters
C) neurotransmitters and vitamins
D) growth hormones and vitamins
E) peptide hormones and neurotransmitters

Question

Quizplus · Accepted Answer

Peptide hormones and neurotransmitters are the two major categories of extracellular signaling molecules that bind to cell surface receptors. Peptide hormones are composed of amino acids and cannot cross the cell membrane, thus they bind to receptors on the cell surface. Neurotransmitters are chemical messengers that transmit signals across a chemical synapse, such as between neurons or between a neuron and a muscle, and also bind to receptors on the cell surface.

The Two Major Categories of Extracellular Signaling Molecules That Bind