sp08 second exam

sp08 second exam - Metabolic Biochemistry / BIBC 102 Second...

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1 Metabolic Biochemistry / BIBC 102 Second Exam / Spring 2008 I. (20 points) You are given a preparation of intact mitochondria in a suspension containing plentiful amounts of oxygen, phosphate, ADP, and malonate, a competitive inhibitor of succinate dehydrogenase. Under these conditions, all TCA cycle intermediates are converted to succinate, which builds up in the mitochondria. In your experiment, you add pyruvate labeled with 14 C in the carbonyl carbon (CH 3 - 14 C(O)- CO 2 ) to this mitochondrial suspension, incubate, and then isolate succinate. Show how you can synthesize succinate starting from pyruvate alone . (This means that you are given a pool of pyruvate molecules and that all carbon atoms in TCA intermediates must be made from these molecules.) Draw the correct structure for each intermediate molecule. Include the names or abbreviations of any other reactants and products (eg, ATP, ADP, Pi, NAD+, NADH, etc), and any required prosthetic groups (eg, biotin, TPP, etc.). And trace the fate of the 14 C label from pyruvate to succinate.
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2 II. (25 points) Fill in all of the enzyme catalyzed reactions which convert the substrate on the upper left to the product on the lower right. Draw the correct structure for each intermediate molecule and the carnitine shuttle (carnitine can be shown as a box with an OH projecting off of it). Include the names or abbreviations of any other reactants and products (e.g., ATP, ADP, Pi, NAD + , FAD, NADH, etc.), any required cofactors (e.g., biotin, TPP, etc.), and indicate subcellular location (cytosol or matrix). O A. CH 3 (CH 2 ) 14 C-O (Cytosol) O O CH 3 (CH 2 ) 12 C SCoA + CH 3 C SCoA (matrix) (matrix) B. Please indicate which one of the above enzymatic reactions is under allosteric regulation , the identity of the allosteric activators and/or inhibitors of this enzyme, and the physiological role of this regulation in a cell.
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3 III. (25 points) (A) Draw a diagram of the overview of proton and electron circuits in mitochondria starting with NADH in the matrix and ADP and P i in the cytosol and ending with the reduction of oxygen to water and the formation of ATP (the diagram in the lecture handout will receive full credit). Label each complex and protein, identify matrix, intermembrane space, and inner membrane, and indicate the flow of protons and electrons. (B) Describe (or illustrate with a diagram) how electron transport is coupled to the formation of ATP, and briefly explain how this coupling accounts for the increased O 2 consumption during aerobic exercise.
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4 IV. (20 points) Answer two of the following three parts (A to C); cross out the part that you don’t wish to have graded or we will cross out part A for you. A.
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This note was uploaded on 08/04/2009 for the course BIBC BIBC 102 taught by Professor Price during the Spring '08 term at UCSD.

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sp08 second exam - Metabolic Biochemistry / BIBC 102 Second...

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