AP BIOLOGY

Detailed explanation-1: -Chemical signals between cells are called ligands. A ligand is a molecule that binds another specific molecule. In the case of cell signaling, the ligand binds a receptor, a protein in or on the target cell. Examples of ligands include hormones and neurotransmitters.

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: -Transduction: When the signaling molecule binds the receptor it changes the receptor protein in some way. This change initiates the process of transduction. Signal transduction is usually a pathway of several steps. Each relay molecule in the signal transduction pathway changes the next molecule in the pathway.

Detailed explanation-4: -Once a ligand binds to a receptor, the signal is transmitted through the membrane and into the cytoplasm. Continuation of a signal in this manner is called signal transduction .

Detailed explanation-5: -The ligand crosses the plasma membrane and binds to the receptor in the cytoplasm. The receptor then moves to the nucleus, where it binds DNA to regulate transcription.