AP BIOLOGY

Detailed explanation-1: -Cellular receptors are proteins either inside a cell or on its surface which receive a signal. In normal physiology, this is a chemical signal where a protein-ligand binds a protein receptor. The ligand is a chemical messenger released by one cell to signal either itself or a different cell.

Detailed explanation-2: -Cell plasma membranes (and a few intracellular membranes as well) contain membrane receptors. These receptors mediate signal transduction for cellular responses to extracellular stimuli. Membrane receptors are usually transmembrane proteins.

Detailed explanation-3: -Membrane receptors are specialized protein molecules attached to or integrated into the cell membrane. Through interaction with specific ligands (e.g., hormones and neurotransmitters), the receptors facilitate communication between the cell and the extracellular environment.

Detailed explanation-4: -Receptors come in many types, but they can be divided into two categories: intracellular receptors, which are found inside of the cell (in the cytoplasm or nucleus), and cell surface receptors, which are found in the plasma membrane.

Detailed explanation-5: -B. Membrane receptors associated with signaling are all integral membrane proteins that can transmit signals through the lipid bilayer. Yes, membrane proteins that function as receptors for cell signaling must penetrate the cell membrane.