AP BIOLOGY

Detailed explanation-1: -Phosphorylation, a major component of signal cascades, adds a phosphate group to proteins, thereby changing their shapes and activating or inactivating the protein. Degrading or removing the ligand so it can no longer access its receptor terminates the signal.

Detailed explanation-2: -Degradation of signaling molecules and dephosphorylation of intermediates of the pathway are two ways signals are terminated within cells.

Detailed explanation-3: -The termination phase of cell signaling requires which of the following? hydrolyzes GTP binding to G protein. Which of the following describes the events of apoptosis? Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests.

Detailed explanation-4: -Receptor inactivation can operate in several ways including removal of the ligand by degradation or sequestration, and desensitization of the target cell. Binding of a ligand to its receptor is a reversible process, as the ligand will ultimately dissociate from the receptor and may be degraded.

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.