AP bio unit 4 notes

cell signaling

reception - target cells detection of a signal molecule (ligand) coming from outside of the cell

• two types of receptor locations

  • intracellular receptors - found inside the plasma membrane in cytoplasm or nucleus; signal mol must cross the plasma membrane and therefore must be hydrophobic

  • plasma membrane receptors/cell-surface receptors - bind to water-soluble ligands

• g protein coupled receptor (GPCR) is a membrane receptor that works with the help of a G protein

  • ligand binds to GPCR; receptor is now active, hanges shape, binds a g protein that is then activated when replaces its GDP with a GTP molecule

  • activatted g protein leaves recceptor, diffuses along membrane, and activates a specific enzye when it binds to it; enzyme triggers the next step in a pathway leading to a cellular response

transduction - binding of the signaling molecule changes the intraccellular domain of the receptor protein; converts the signal to a form that can bring about a specific cellular response

response - specific cellular response to the signal molecule