LIFE SCIENCE

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: -Small, hydrophobic ligands can pass through the plasma membrane and bind to intracellular receptors in the nucleus or cytoplasm. In the human body, some of the most important ligands of this type are the steroid hormones.

Detailed explanation-3: -Within biochemistry, a ligand is defined as any molecule or atom that irreversibly binds to a receiving protein molecule, otherwise known as a receptor.

Detailed explanation-4: -Regardless of the nature of the signal, the target cell responds by means of a specific protein called a receptor, which specifically binds the signal molecule and then initiates a response in the target cell.