exam 2 - 1 Q1.Which of the following is true? 1) 2) 3) 4)...

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1 Q1.Which of the following is true? 1) Enzymes force reactions to proceed in only one direction. 2) Enzymes alter the equilibrium of the reaction. 3) Enzymes alter the standard free energy of the reaction. 4) All of the above. 5) None of the above. Q2. When substrate concentration is much greater than Km, the rate of catalysis is almost equal to 1) Kd. 2) kcat. 3) Vmax. 4) All of the above. 5) None of the above. Q3. If you carried out site-directed mutagenesis of chymotrypsin, changing serine 195 to isoleucine, what would you expect? 1) a large change in K M 4) 1 and 3 2) a small change in K M 5) 2 and 3 3) a large change in k cat Q4. Which of the following statements about a plot of V 0 vs. [S] for an enzyme that follows Michaelis-Menten kinetics is false ? 1) As [S] increases, the initial velocity of reaction V 0 also increases. 2) At very high [S], the velocity curve becomes a horizontal line that intersects the y-axis at K m . 3) K m is the [S] at which V 0 = 1/2 V max . 4) The shape of the curve is a hyperbola. 5) The y-axis is a rate term with units of μm/min. Q5. Michaelis and Menten assumed that the overall reaction for an enzyme-catalyzed reaction could be written as k 1 k 2 E + S ES E + P k -1 Using this reaction, the rate of breakdown of the enzyme-substrate complex can be described by the expression: 1) k 1 ([E t ]  [ES]). 2) k 1 ([E t ]  [ES])[S]. 3) k 2 [ES]. 4) k -1 [ES] + k 2 [ES]. 5) k -1 [ES]. Q6. For an enzymatic reaction obeying the Michaelis–Menten equation to reach 3/4 its maximum velocity (perhaps a useful hint: what happens when you set v o = Vmax/2), 1) [S] would need to be 2 K M 2) not enough information is given to make this calculation 3) [S] would need to be 50% greater than K M 4) [S] would need to be 3 K M 5) [S] would need to be 3/4 K M
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2 Q7. Fructose (a ketohexose) can cyclize to (a) 1) pyranose ring. 2) furanose ring. 3) both pyranose and furanose ring forms. 4)
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This note was uploaded on 11/04/2011 for the course BIOL 430 taught by Professor Lspremulli during the Fall '08 term at UNC.

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exam 2 - 1 Q1.Which of the following is true? 1) 2) 3) 4)...

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