Practice Exam3 2009

Practice Exam3 2009 - BBMB404 Exam 3 - Fall 2009 BBMB 404...

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BBMB404 Exam 3 - Fall 2009 1 BBMB 404 – Fall 2009 Exam 3 – 9 Dec. 2009 1. 7TM/serpentine receptors respond to a wide variety of different stimuli. How is their common signaling mechanism most directly altered to create appropriate response? a) There is a different G ! protein specific to each such receptor. b) Combinations of different subunits of the heterotrimeric G-proteins are selective for these receptors and downstream effectors. c) There is a different small G-protein specific to each such receptor. d) There are different adaptor proteins that provide the specificity for downstream effectors. e) The coupled small G-proteins contain different arrangements of modular domains that lead to specificity for different downstream effectors. 2. Which of the following explains why adrenaline signaling can respond to an initial release of the hormone, yet still respond later to an additional release without an intervening decrease in concentration of adrenaline? a) The bound adrenaline diffuses away. b) Phosphatases dephosphorylate all the effector proteins. c) The receptor is phosphorylated leading to binding of a “blocking” protein. d) The activated G ! s hydrolyzes the activating GTP. e) The downstream second messengers are broken-down and re-sequestered in the ER. 3. Phospholipase C ß provides an example of feedback activation due to the presence of what modular domain? a) C2 domain b) G protein interaction domain c) phospholipase domain d) pleckstrin homology (PH) domain e) Src homology 3 (SH3) domain 4. Which Ca 2+ binding domain is found in calmodulin? a) C1 domain b) C2 domain c) SH1 domain d) SH2 domain e) EF hand domain 5. Which of the following is NOT a part of the common mechanism of tyrosine protein kinase receptors? a) ligand-induced dimerization b) cross-phosphorylation c) adapter/scaffolding proteins d) downstream protein kinases e) downstream protein phosphatases
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BBMB404 Exam 3 - Fall 2009 2 6. Which of the following is not a commonly used second messenger in signaling? a) cyclic AMP (cAMP) b) Ca 2+ c) diacylglycerol (DAG) d) inositol trisphosphate (IP 3 ) e) all of the above are second messengers 7. The protein kinases PKA and PKC are activated by binding of what second messengers, respectively? a) Ca 2+ and cGMP b) DAG and Ca 2+ c) Ca 2+ and IP 3 d) cAMP and IP 3 e) none of the above 8. Protein phosphorylation is often used in signaling pathways. How does this affect the modified protein? a) The addition of phosphate activates the protein. b) The addition of the negative charges from phosphate leads to a change in conformation. c) This targets the protein for inactivation and degradation. d) This energizes the protein. e) This drives localization of the protein to the membrane.
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Practice Exam3 2009 - BBMB404 Exam 3 - Fall 2009 BBMB 404...

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