sp09 midterm exam

sp09 midterm exam - Metabolic Biochemistry / BIBC 102...

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Metabolic Biochemistry / BIBC 102 Midterm Exam / Spring 2009 I. (20 points) Fill in all of the enzyme catalyzed reactions which convert glycogen to lactate . Draw the correct structure for each intermediate molecule, showing the correct position of the hydrogen atoms at each carbon atom. 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.). (Note: you do not need to give the correct name for each intermediate molecule or the correct name of the enzyme to receive full credit. Partial credit will, however, be given for the correct name of an intermediate structure if the structure itself is incorrect.) Glycogen (draw the 2 terminal sugar subunits of the polymer only) lactate (draw structure)
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2 II. (20 points) A. Given a mitochondrial extract with all of the enzymes and cofactors normally found inside mitochondria but lacking pyruvate dehydrogenase completely, show how pyruvate, CO2, and acetyl CoA can be used to form succinate when succinate dehydrogenase is inhibited by malonate. (Assume there is no oxaloacetate initially present.) Draw the correct structure for each intermediate molecule, showing the correct position of the hydrogen atoms at each carbon atom. 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, lipoate, etc.). B. Show the path of 14 C label in each molecule above starting with 14 C label in the methyl carbon of pyruvate ( 14 CH 3 -C(O)-CO 2 -).
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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) Indicate on this diagram the relevant electron carriers in each complex of electron transport (e.g., FeS, cytochrome a 3 , Cu, FMN, etc.).
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4 IV. (20 points). When oxygen is removed from a suspension of yeast cells using glucose for energy, the rate of glucose consumption increases dramatically and ethanol begins to accumulate in the media. This effect, first observed by Pasteur, is characteristic of most cells capable of both aerobic and anaerobic utilization of glucose. A. Why did ethanol begin to accumulate when oxygen was removed? B . Assuming the ATP needs of the cell are constant, what will be the relative increase in glucose consumption? In order to receive credit, you must show your calculations. C.
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sp09 midterm exam - Metabolic Biochemistry / BIBC 102...

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