Final answer:
A first messenger binding to a receptor with an ion channel leads to the opening of the channel, allowing specific ion flow that can alter membrane potential and elicit cellular responses such as action potentials.
Step-by-step explanation:
When a first messenger binds to and activates a membrane-bound receptor that contains an ion channel, it can lead to a series of cellular events. The first messenger usually refers to a hormone or neurotransmitter that binds to the cell's plasma membrane receptors, leading to signal transduction pathways inside the cell.
Ion channel-linked receptors, when bound by a ligand such as a neurotransmitter, undergo a structural change that allows them to function as a channel. These channels are made up of membrane-spanning regions rich in hydrophobic amino acids, which are necessary to interact with the plasma membrane's hydrophobic interior. Simultaneously, the channel's inner surface has hydrophilic amino acids to permit ion passage.
Upon ligand binding, the resulting structural change opens the channel and allows specific ions to flow through. This flow of ions can change the cell's membrane potential, leading to electrical signals such as action potentials in neurons. This process is fundamental in cellular communication, especially in nerve and muscle cells where neurotransmitters released by neuron action potentials bind to receptors on the motor end plate, causing ion channels to open and initiate muscle contraction.