AP BIOLOGY

Detailed explanation-1: -1. Reception: A cell detects a signaling molecule from the outside of the cell. A signal is detected when the chemical signal (also known as a ligand) binds to a receptor protein on the surface of the cell or inside the cell.

Detailed explanation-2: -A ligand that can bind to and alter the function of the receptor that triggers a physiological response is called a receptor agonist. Ligands that bind to a receptor but fail to activate the physiological response are receptor antagonists.

Detailed explanation-3: -Ion Channel Receptors When a ligand binds an ion channel receptor, a channel through the plasma membrane opens that allows specific ions to pass through. This process requires a specialized membrane-spanning region of the receptor.

Detailed explanation-4: -Three Stages of Cell Signaling First, reception, whereby the signal molecule binds the receptor. Then, signal transduction, which is where the chemical signal results in a series of enzyme activations. Finally, the response, which is the resulting cellular responses.

Detailed explanation-5: -Paracrine signaling Often, cells that are near one another communicate through the release of chemical messengers (ligands that can diffuse through the space between the cells). This type of signaling, in which cells communicate over relatively short distances, is known as paracrine signaling.