Question Set 4 1. What’s the best evidence for an early evolution of cell communication mechanisms? • The best evidence is the similarity between the molecular details of signal transduction, and cell signaling all together in yeast and mammals. o The last common ancestor of yeast and mammals lived over a billion years ago. 2. How does the toxin of the organism that causes cholera have its effects? • The cholera chemically modifies a G protein that regulates salt and water secretion. This G protein remains stuck in active form and therefore continues to make cyclic AMP by stimulating adenylyl cyclase. The high concentration of cAMP causes intestinal cells to secrete large amounts of water and salts into the intestines, causing profuse diarrhea and possibly death. 3. Pick two of the following and tell how they would be used to design a drug to keep blood sugar levels low. • Using cAMP and G proteins we could make a drug that lowers blood sugar levels by having some type of message carried out to by G protein
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