AP BIOLOGY

Detailed explanation-1: -A ligand is a molecule that binds another specific molecule, in some cases, delivering a signal in the process. Ligands can thus be thought of as signaling molecules. Ligands interact with proteins in target cells, which are cells that are affected by chemical signals; these proteins are also called receptors.

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: -Cell-surface receptors. Cell-surface receptors are membrane-anchored proteins that bind to ligands on the outside surface of the cell.

Detailed explanation-4: -Molecules that bind to receptor sites are known as ligands. Hormones, neurotransmitters, and drugs are examples of ligands. They are able to fit into specific receptor sites in the same way keys are able to fit into specific locks.

Detailed explanation-5: -Signaling molecules are often called ligands, a general term for molecules that bind specifically to other molecules (such as receptors). The message carried by a ligand is often relayed through a chain of chemical messengers inside the cell.