[Campbell Biology P.281] According to Concept 11.3, which of the following statements about ... | Practice Question

According to Concept 11.3, which of the following statements about second messengers are true? Select all that apply

  • A: They are typically small, nonprotein, water-soluble molecules or ions.
  • B: They facilitate rapid broadcast of signals throughout the cell.
  • C: Examples include cyclic AMP (cAMP), Ca2+, diacylglycerol (DAG), and inositol trisphosphate (IP3).
  • D: They are often activated by enzymes like adenylyl cyclase.
  • E: They are always large proteins that phosphorylate other molecules.

Explanation

Second messengers are crucial in signal transduction, characterized by being small, nonprotein, water-soluble molecules or ions that can diffuse quickly throughout the cell to broadcast signals. Key examples mentioned are cyclic AMP cAMP , Ca2+, diacylglycerol DAG , and inositol trisphosphate IP3 . Enzymes like adenylyl cyclase play a role in their production e.g., cAMP from ATP . The statement that they are always large proteins that phosphorylate other molecules describes protein kinases, not second messengers.