Question

7. Which of the following statements about second messengers is false? (a) Ca2+ ions and cAMP are examples of second messengers (b) They are used as intracellular signals in signal transduction pathways, following activation of a receptor. (c) They are produced in very small amounts following cell activation, and are difficult to detect experimentally. (d) They activate other molecules, such as kinases (e) There are mechanisms that enable the messages to be “turned off” after they are generated

Answer 1

a) TRUE :  There are 3 major classes of second messengers: cyclic nucleotides (e.g., cAMP and cGMP) inositol trisphosphate (IP3) and diacylglycerol (DAG) calcium ions (Ca2+)

b) TRUE :  Second messengers are the substances that enter the cytoplasm and act within the cell to trigger a response. In essence, second messengers serve as chemical relays from the plasma membrane to the cytoplasm, thus carrying out intracellular signal transduction.

Signal Transduction Pathways

Transmission is continued either by a series of biochemical changes within the cell or by modification of the cell membrane potential by the movement of ions in or out of the cell. " Receptors " that initiate biochemical changes can do so either directly via intrinsic enzymatic activities within the receptor or by activating intracellular messenger molecules.

c) TRUE

d) FALSE