AP BIOLOGY

Detailed explanation-1: -Why can a signaling molecule cause different responses in different cells? Different cells have membrane receptors that bind to different sides of the signaling molecule. The transduction process is unique to each cell type; to respond to a signal, different cells require only a similar membrane receptor.

Detailed explanation-2: -Receptors are generally transmembrane proteins, which bind to signaling molecules outside the cell and subsequently transmit the signal through a sequence of molecular switches to internal signaling pathways.

Detailed explanation-3: -In addition, signaling molecules differ in their mode of action on their target cells. Some signaling molecules are able to cross the plasma membrane and bind to intracellular receptors in the cytoplasm or nucleus, whereas most bind to receptors expressed on the target cell surface.

Detailed explanation-4: -Cell-surface receptors come in three main types: ion channel receptors, GPCRs, and enzyme-linked receptors.