Study Guide 10
Last revised: Wednesday, March 6, 2002
Topic: Cell Communication
Chapter 11

  1. Give at least two examples of situations in which cells alter their activity in response to external signals.
  2. What does the term "signal transduction" mean? What are the 3 stages of cell signaling?
  3. We will concentrate on "G-proteins" as our major example of signal transduction mechanisms. Draw a diagram of a simple G-protein signal pathway, indicating how each of the following components is situated relative to the cell membrane: receptor protein, G protein, effector enzyme. What does the "G" stand for? Which of these components (receptor protein, G protein, effector enzyme) are allosteric proteins, capable of alternating between active ("on") and inactive ("off") configurations?
  4. How common are G-protein linked signaling pathways? Are they related to health/disease states?
  5. We won't have time to talk about tyrosine-kinase receptors and ion-channel receptors (pp. 192-195 in text) during class. Do take a few minutes to examine figures 11.8 and 11.9 so you can recognize what these
  6. What is a protein kinase? What result does it bring about?
  7. Many signaling pathways involve multiple kinases, each of which activates another kinase, which activates yet another, etc., until the final target enzyme is activated. What is the advantage of such a scheme?
  8. What is a "second messenger"? How does it differ from a "first messenger"?
  9. What is cyclic AMP? [Note that the enzyme "adenyl cyclase", which makes cyclic AMP, is often the membrane-bound target of a G-protein.] What role does cyclic AMP perform in most cells? Be able to recognize the structure of cyclic AMP (see Fig. 11.11)
  10. Ca++ ion is widely used as a second messenger that controls different events than those controlled by cAMP. How does the intracellular and extracellular concentration of Ca++ compare? On which side of the cell membrane is most Ca++? What happens inside a cell when Ca++ suddenly increases? We won't discuss the inositol triphosphate system in class, but do spend a few minutes examining Figs. 11.13 and 11.14 to see how Ca++ can serve to regulate various cell activities.

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