Final answer:
A ligand-gated channel is an ion channel that opens in response to a ligand binding, allowing ions to change the cell's charge, importantly utilized in neural communication. G-protein-linked receptors activate a G-protein, initiating further cellular signaling rather than directly opening ion channels. These pathways are vital for cell communication and are implicated in many diseases.
Step-by-step explanation:
A ligand-gated channel is a type of ion channel in the cell membrane that opens and closes in response to the binding of a chemical signal, or ligand. Specifically, these channels open to allow the flow of ions such as sodium, calcium, and potassium across the membrane, altering the electrical charge and triggering a cellular response. This mechanism is essential for processes like synaptic transmission in the nervous system, where neurotransmitters act as ligands to initiate nerve impulses.
By contrast, G-protein-linked receptors do not directly form ion channels. Rather, they activate an associated G-protein, which then interacts with other membrane proteins that can either be ion channels or enzymes triggering further signaling events inside the cell.
Nonpolar signaling molecules like steroids typically diffuse through the cell membrane and do not interact with ligand-gated channels; they bind to internal receptors inside the target cell instead. Cell signaling pathways are crucial for cellular communication and can be disrupted in various diseases.