Exam 3 - Cell Biology / Cell Biochemistry BIOL 4374 / BCHS...

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Cell Biology / Cell Biochemistry BIOL 4374 / BCHS 4313 Exam 3 Apr 6, 2009 Read each question carefully . Chose the single best answer to each of the following questions. In some cases, key words are emphasized in bold italics font 1. The gaseous messenger, nitric oxide, is produced by nitric oxide synthase from which of the following precursors. a. nitrate b. nitrous oxide c. alanine d. arginine e. asparagine 2. Nitric oxide activates which of the following enzymes? a. adenylyl cylcase b. guanylyl cyclase c. phospholipase C d. cAMP phosphodiesterase e. cGMP phosphodiesterase 3. Which of the following intercellular messengers does NOT signal through a nuclear receptor? a. estradiol b. retinoic acid c. thyroxine d. vitamin D3 e. all of the above signal through nuclear receptors 4. Cholera toxin disrupts cell biochemistry by covalently modifying the alpha subunit of which of the following trimeric G proteins? a. Gs b. Gi c. Go d. Gq e. none of the above 5. During embryonic development, the fate of uncommitted cells is often determined by their location along an extracellular gradient of a diffusible “morphogen”. This is an example of which of the following signaling strategies? a. endocrine signaling b. paracrine signaling c. contact dependent signaling d. synaptic signaling e. none of the above 6. Which of the following is false regarding protein kinase A? a. it is activated by the binding of cAMP to the catalytic subunit b. it phosphorylates and activates the CREB protein c. it mediates the effects of G-protein coupled receptors that signal through Gs d. it is a serine-threonine kinase e. all of the following are true about protein kinase A
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7. Most G-protein coupled receptors (GPCRs) encoded by the human genome signal through which of the following intracellular messengers? a. cAMP d. IP3 b. cGMP e. diacylglycerol c. calcium 8. In rod photoreceptors, light-activated rhodopsin signals through the trimeric G-protein “transducin”, resulting in the activation of which of the following enzymes? a. adenylyl cyclase b. guanylyl cyclase c. cAMP phosphodiesterase d. cGMP phosphodiesterase e. protein kinase A 9. GRK kinases phosphorylate GPCRs at multiple sites, marking them for desensitization. Which of the following proteins binds to phosphorylated GPRCs resulting in receptor desensitization? a. adaptin b. sequestin c. receptin d. arrestin e. inactin 10. A ligand-bound GPCR behaves like which of the following? a. a protein kinase b. a protein phosphatase c. a guanine nucleotide exchange factor d. a GTPase activating factor e. a nuclear localization signal 11. Which of the following signaling enzymes creates sites on the plasma membrane for the recruitment and activation of protein kinase C? a. adenylyl cyclase
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Exam 3 - Cell Biology / Cell Biochemistry BIOL 4374 / BCHS...

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