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BIO311c-Worksheet4-Metabolism-Answerkey-2006 - WORKSHEET 4...

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Unformatted text preview: WORKSHEET 4 K. SATHASIVAN Chapter 6. Metabolism Name _______________ANSWER KEY___________________________ Read each question carefully, select the best answer for multiple-choice questions and circle the right answer. For the rest of the questions, write your answers within the given space. A. Multiple Choice Questions BIO 311c 1. Burning of gasoline to drive the car is an example of a. exothermic reaction b. endothermic reaction c. endergonic reaction d. cooling reaction e. anabolic reaction RoundUp herbicide is a competitive inhibitor of the enzyme EPSP- synthase in an amino acid biosynthesis pathway. RoundUp can alter the a. Vmax of this enzyme b. Km for its substrate(s) c. both a and b d. regulatory site in enzyme e. none of the above. The change in free energy (ΔG) is best explained by the following equation. a. ΔG = ΔH + TΔS b. ΔG = ΔH - T∆S c. ΔG= ΔH + T - ΔS d. ΔG= TΔS - ΔH e. ΔG= ΔH - T + ΔS ATP is utilized in driving many cellular work because it a. uses lots of bond energy for hydrolysis b. absorbs heat and make the body cool c. releases free energy during hydrolysis d. it helps in releasing O2 from photosynthesis. e. is an anabolic process important for survival Enzymes are biological catalysts that can increase the rate of a biochemical reaction by the following mechanism. a. increase entropy and enthalpy. b. denature the reactants. c. decrease the concentration of reactants. d. lower the energy of activation. e. increase the free energy of activation. Acetolactate synthase is a key regulatory enzyme in the beginning of the valine biosynthetic pathway. When valine accumulates above a specific concentration, it inhibits the activity of acetolactate synthase. The mechanism of action of valine is a. competitive inhibition b. non-competitive inhibition c. feedback regulation d. chemical modification e. irreversible inhibition 2. 3. 4. 5. 6. 1 Use the graph below to answer questions 7 and 8. Enzyme +Substrate alone V Enzyme +Substrate + X [S] 7. Which of the following statement is true about the enzyme used in the above study? a. it shows cooperativity b. it is a simple enzyme. c. it shows a sigmoidal response d. it is an allosteric enzyme e. all the above Based on the above graph, we can tell the compound-X is a/an a. competitive inhibitor b. non-competitive inhibitor d. irreversible inhibitor e. feedback inhibitor c. activator 8. 9. Phosphoglucomutase catalyzes the reaction of Glucose 6-phosphate (G6P) to Fructose 6-phosphate (F6P). You are starting the reaction in test tube with the 0.8 M substrate (G6P) and let the reaction reach equilibrium. The product (F6P) concentration at equilibrium is 0.6 M. There are no intermediates in this reaction and no products at the beginning. The Keq for this reaction is a. 1.5 b. 0.75 c. 2.0 d. 3.0 e. 4.0 Keq = 0.6/0.8-0.6 = 3.0 b. organic cofactors d. reducing agents 10. Both NAD+ and FAD are a. enzymes c. inorganic cofactors e. amino acids 11. The first law of thermodynamics states that the energy a. can neither be created nor destroyed. b. the total energy of the universe is constant c. the energy can be transferred or transformed d. all a, b and c are correct. e. The energy transfer results in increased entropy The enzyme activity can be regulated by all the following EXCEPT a. activators b. competitive inhibitors c. non-competitive inhibitors d. phosphorylation e. degradation 12. 2 B. Short Answer Questions. 1. Given a concentration of reactant X = 1M at equilibrium, calculate the concentration of product Y at equilibrium given that Keq= 10 for a reaction , what percentage of the reactant is converted to product? If the Keq is 10, then, the product Y = 10 M. Percent of substrate converted to product is (10/10 +1) x 100 = 90.9 % If the Keq = 2, then the product Y = 2 and Percent of substrate converted to product is ½ x 100 = 50% 2. Give an example of a spontaneous reaction those results in a decrease in entropy. Condensation on a cup of cold water. Rain formation. Snow formation. 3. Give an example of a spontaneous (exergonic) reaction that is endothermic. Ice pack, using ice to cool down a cup of water or coke, dissolving sugar in hot coffee. Define the following terms (see book) 1. Free Energy 2. Entropy 3. Enthalpy 4. Exergonic reaction 5. Endothermic reacion 6. ATP 7. Energy coupling 8. Vmax 9. Km 10. Competitive inhibition 11. Active site 12. Allosteric enzyme 13. Feed back Inhibition 3 7. Plot the rate of reaction (V) vs. the substrate concentration ([S]). Then, given the following rates of reaction for different substrate concentrations in the absence and presence of an inhibitors A and B, estimate the Vmax with and without inhibitor and determine the type of inhibitor. Learn to understand the pattern of kinetics in this data. [S] (mM) .003 .005 .010 .030 .090 Velocity (mM/minute) No Inhibitor Inhibitor A .104 .041 .145 .064. .225 .113. .338 .226. .405 .338. Inhibitor B .021 .029 .045 .068 .081 No Inhibitor Vmax Km Inhibitor type 0.405 0.01 N/A Inhibitor A >0.338 0.03 Competitive Inhibitor B >0.081 0.01 Non-Competitive 4 ...
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