practice_exam_3 - _ Name CHM 3218 Spring 2008 Practice...

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__________________________________ Name 1 CHM 3218 Spring 2008 Practice Examination #3 University of Florida Honor Code Statement: "On my honor, I have neither given nor received unauthorized aid in doing this assignment." __________________________________ Student signature Instructions : You would have two hours to complete this exam. All books, notes and other aids would be prohibited, but calculators and molecular models would be allowed. Be sure to budget your time and answer questions briefly but completely. To receive partial credit for incorrect answers, be sure to show your work, particularly in problems involving calculations. Write your name on each page. 1. The citric acid cycle along with the glyoxalate shunt are key pathways in metabolism. Use your knowledge of the reactions discussed during lecture to answer the following questions. ( Total 41 points ). - O 2 C CO 2 - O - O 2 C 2 - OH - O 2 C 2 - - O 2 C CO 2 - CO 2 - O CoAS - O 2 C O CO 2 - - O 2 C OH CO 2 - 2 - - O 2 C CO 2 - HO 2 - oxaloacetate succinyl-CoA citrate malate fumarate isocitrate succinate α -ketoglutarate CH 3 SCoA O acetyl-CoA 2 CO 2 CoASH CoASH +GTP GDP +P i H 2 O CoASH +H 2 O H CO 2 - O glyoxalate + NAD + NADH a. For the three reactions with boxes near the arrows, predict the cofactor (if any) most likely to be involved in this reaction and write the name or abbreviation in the space provided. Note that names and complete structures of all of the cofactors discussed in this course can be found on the last page of this exam. ( 3 points each ).
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__________________________________ Name 2 b. Use curved arrows to show the chemical mechanism used by citrate synthase, which catalyzes the reaction of water, acetyl-CoA plus oxaloacetate to form citrate plus CoASH. Be sure to show the correct amino acid side-chains used for acid-base catalysis by this enzyme . ( 8 points ). c. Aconitase catalyzes the interconversion of citrate and isocitrate. Would you predict that the equilibrium position for this reaction would strongly favor products, strongly favor reactants or strongly favor neither side. Briefly explain your answer. ( 4 points ).
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__________________________________ Name 3 d. Use curved arrows to show the chemical mechanism of the reaction catalyzed by aconitase. You may use acid-base catalysis as necessary. ( 8 points ). e. Malic enzyme catalyzes the interconversion of malate plus NAD + and oxaloacetate plus NADH. Use curved arrows to show the chemical mechanism for this enzyme-mediated reaction. You may use acid-base catalysis as necessary. ( 8 points ).
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__________________________________ Name 4 f.
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This note was uploaded on 05/21/2008 for the course BCH 3218 taught by Professor Johnsteward during the Spring '08 term at University of Florida.

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practice_exam_3 - _ Name CHM 3218 Spring 2008 Practice...

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