Exam 2 Questions foundations of bio

Exam 2 Questions foundations of bio - Problem Set Enzymes...

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Problem Set - Enzymes Answers 1) An enzyme catalyzes the reaction A → B. The rate of the reaction was measured as a function of the initial concentration of A. The following data was obtained: [A] Reaction Rate (v) 0.05 0.08 0.1 0.16 0.5 0.79 1 1.6 5 7.3 10 13 50 40 100 53 500 73 1000 76 5000 79 10,000 80 20,000 80 a) What is the Km of the enzyme for the substrate A? b) What is the value of v when [A] = 43? The above data was plotted as 1/v vs 1/[A], and a straight line was obtained. c) What is the value of the y-intercept of the line? d) What is the value of the x-intercept of the line? 2) You measure the rate of an enzyme reaction as a function of substrate concentration in the presence and absence of an inhibitor. The following data is obtained: [S] Reaction Rate (v) Km=Vmax/2 - Inhibitor +Inhibitor .0001 33 17
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.0002 50 29 .0005 71 50 .001 83 67 .002 91 80 .005 96 91 .01 98 95 .02 99 98 .05 100 99 .1 100 100 .2 100 100 a) What is the Vmax (in the absence of inhibitor) ? _________ b) What is the Km (in the absence of inhibitor) ? _________ c) When [S] = .0004, what will the rate be in the absence of inhibitor? ___________ d) When [S] = .0004, what will the rate be in the presence of inhibitor? ___________ 3) An enzyme can catalyze a reaction with either of 2 substrates, S1 or S2. The Km for S1 was found to be 2.0 mM, and the Km for S2 was found to be 20 mM. A student determined that the Vmax was the same for the two substrates. Unfortunately he lost the page of his notebook and needed to know the value of Vmax. He carried out two reactions, one with 0.1 mM S1, the other with 0.1 mM S2. Unfortunately, he forgot to label which reaction tube contained which substrate. Determine the value of Vmax from the results he obtained: Tube number Rate of formation of product 1 0.5 2 4.8 4) An enzyme catalyzes the reaction A → B. The rate of the reaction was measured as a function of the initial concentration of A. The following data was obtained: [A] Reaction rate (v) 0.05 0.4 0.1 0.8 0.5 3.8 1 7 5 27 10 40
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50 67 100 73 500 78 1000 79 5000 80 10,000 80 The same experiment was carried out in the presence of a compound which is known to be a competitive inhibitor of the enzyme. Unfortunately most of the tubes were spilled so only one of the experimental data points was obtained (see below). Fill in the missing values of v which you would predict, based upon the data which was obtained. [A] Reaction rate (v) 1.0 10 20 40 10,000 Answers to enzymes problem set 1) a) 50 b) 37 c) 0.0125 d) -0.02 2) a) 100 b) 0.0002 c) 66.7 d) 44.4 3) 101 4) [A] v 1.0 3.8 10 27 20 40 10,000 80 Sample questions for exam 2 Answers 1) An enzyme can make a reaction go faster by
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a. decreasing the free energy of the transition state b. increasing the free energy of the reactants c. decreasing the difference between the free energy of the reactants and the free energy of the transition state d. all of the above e. none of the above
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This note was uploaded on 05/19/2010 for the course BIO 201 taught by Professor Frenkel/cervantes during the Spring '10 term at Rutgers.

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Exam 2 Questions foundations of bio - Problem Set Enzymes...

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