AP BIOLOGY

Detailed explanation-1: -An acetylcholine receptor (green) forms a gated ion channel in the plasma membrane. This receptor is a membrane protein with an aqueous pore, meaning it allows soluble materials to travel across the plasma membrane when open.

Detailed explanation-2: -The ligand-gated ion channel superfamily includes nicotinic acetylcholine receptors (nAChRs), adenosine triphosphate (ATP) receptors, -aminobutyric acid (GABA), glutamate, glycine, and 5-hydroxytryptamine (5-HT) receptors (Dent, 2010).

Detailed explanation-3: -Receptors can be divided into four basic classes on the basis of their structure and mechanism of action: (1)ligand-gated ion channels, (2)G protein–coupled receptors (GPCRs), (3)enzyme-linked receptors, and (4)nuclear receptors (Table 3.1; Figs.

Detailed explanation-4: -Cell-surface receptors come in three main types: ion channel receptors, GPCRs, and enzyme-linked receptors. When a ligand binds an ion channel receptor, a channel through the plasma membrane opens that allows specific ions to pass through.