AP BIOLOGY

Detailed explanation-1: -In a typical example, signaling molecules first bind to the extracellular domains of two nearby receptor tyrosine kinases. The two neighboring receptors then come together, or dimerize.

Detailed explanation-2: -As already noted, all signaling molecules act by binding to receptors expressed by their target cells. In many cases, these receptors are expressed on the target cell surface, but some receptors are intracellular proteins located in the cytosol or the nucleus.

Detailed explanation-3: -2. 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.

Detailed explanation-4: -Cells have proteins called receptors that bind to signaling molecules and initiate a physiological response. Different receptors are specific for different molecules.

Detailed explanation-5: -The three steps to cell signaling are reception, transduction, and response. In reception, a cell signaling molecule binds to a receptor protein on the cell membrane or inside the cell if the signaling molecule is hydrophobic and can pass through the membrane.