CHEM 120 Exam 3 KEY

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Part I: Multiple Choice (3 points each, 60 pts total, No guessing correction, so answer ALL questions) Note, only questions that are marked as such might have multiple correct answers. E 1. Which of... the following aldopentoses is the sugar in RNA? D 2. Which of the following polysaccharides contains -1,4-glycoside linkages? Mark all that apply a) amylose b) amylopectin c) glycogen d) cellulose A, D 3. Which of the following polysaccharides are unbranched? Mark all that apply a) amylose b) amylopectin c) glycogen d) cellulose Use the following choices to answer questions 4-6. CH2OH CH2OH O OH HO CH2OH O OH O OH CH2OH O O CH2OH O OH OH OH CH2OH CH2OH O OH HO O D E HO CH2OH OH OH A OH HO B OH OH O O OH OH O OH OH HOCH2 O OH HO OH CH2OH C 4. Which one of these structures is lactose? E 5. Which one of these structures is sucrose? A 6. Which one of these structures is maltose? Part I /60 Part II /24 Part III /40E 7. For tertiary protein structures, the most important force is A) disulfides that lock the structure in place B) hydrophobic interactions C) hydrogen bonding D) hydrogen bonds made by the peptide backbone E) All of the above are important and can make significant contributions E 8. Enzymes can be slowed down or stopped by which of the following mechanisms. A) Competitive inhibition B) Covalent modification C) Allosteric inhibition D) Irreversible inhibition E) All of the above Use the following choices to classify the enzymatic reaction shown in questions 24-27. A) a transferase B) a lyase C) an isomerase D) a hydrolase E) a ligase AB) an oxidoreductase (bubble in both letters for this answer) D 9. AB 10. A 11. B 12.B 13. Which one of these statements about enzymatic reactions is true A) Enzymes can convert all the substrate to product B) An enzyme cannot change the point of equilibrium for a reaction C) An enzyme works in part by stabilizing the product more than the reactant D) Enzymes are denatured only by heating or acid E) Enzymes can only work in living cells A, C 14. Bubble all of the following that are true for noncompetitive inhibitors. Bubble in all that are correct. A) The inhibitor binds at a site other than the active site B) The inhibitor structure resembles the substrate/product structure C) The inhibitor distorts the shape of the enzyme making active site inaccessible or inefficient D) The inhibitor directly blocks the substrate from accessing the active site E) The inhibitor irreversibly modifies the enzyme [Show More]

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