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Unformatted text preview: Chapter 12 Biosignaling Multiple Choice Questions 1. Molecular mechanisms of signal transduction Page: 420 Difficulty: 2 Which of the following is not involved in the specificity of signal transduction? A) Interactions between receptor and signal molecules B) Location of receptor molecules C) Structure of receptor molecules D) Structure of signal molecules E) Transmembrane transport of signal molecules by receptor molecules 2. Molecular mechanisms of signal transduction Page: 421 Difficulty: 2 Scatchard analysis can provide information on: A) enzyme cascades. B) enzyme mechanisms. C) gated ion channels. D) protein phosphorylation. E) receptor-ligand interactions. 3. General Features of Signal Transduction Page: 422 Difficulty: 2 Which of the following statements concerning receptor enzymes is correct? A) They are not usually membrane-associated proteins. B) They contain an enzyme activity that acts upon a cytosolic substrate. C) They contain an enzyme activity that acts upon the extracellular ligand. D) They have a ligand-binding site on the cytosolic side of the membrane. E) They have an active site on the extracellular side of the membrane. 4. General Features of Signal Transduction Page: 422 Difficulty: 2 Guanyl cyclase receptor enzymes: A) are all membrane-spanning proteins. B) are examples of ligand-gated ion channels. C) catalyze synthesis of a phosphate ester. D) catalyze synthesis of a phosphoric acid anhydride. E) require hydrolysis of ATP in addition to GTP. Chapter 12 Biosignaling 5. G protein-coupled receptors and second messengers Page: 424 Difficulty: 1 Serpentine receptors: A) are examples of G (GTP-binding) regulatory proteins. B) are mainly involved in the regulation of ion transport. C) are present in prokaryotic cells but not in eukaryotic cells. D) are present in the nucleus and affect gene expression. E) have multiple membrane-spanning helical domains. 6. G protein-coupled receptors and second messengers Pages: 426-427 Difficulty: 2 Cholera and pertussis toxins are: A) enzyme inhibitors. B) enzyme modifiers. C) enzymes. D) G protein signal transduction disrupters. E) all of the above. 7. G protein-coupled receptors and second messengers Page: 428 Difficulty: 2 Protein kinase A (PKA) is: A) activated by covalent binding of cyclic AMP. B) affected by cyclic AMP only under unusual circumstances. C) allosterically activated by cyclic AMP. D) competitively inhibited by cyclic AMP. E) noncompetitively inhibited by cyclic AMP. 8. G protein-coupled receptors and second messengers Page: 429 Difficulty: 2 Which of the following is not involved in signal transduction by the -adrenergic receptor pathway? A) ATP B) Cyclic AMP C) Cyclic GMP D) GTP E) All of the above are involved....
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