Question

fill in the blank question
ion channels that respond to neurotransmitter molecules are described as gated.
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Explanation:

Neurotransmitter molecules are chemical messengers. Ion channels that open or close in response to the binding of these chemical messengers (neurotransmitters) are called ligand - gated ion channels. A ligand is a molecule that binds to another (usually larger) molecule. In this case, the neurotransmitter is the ligand.

Answer:

ligand