sp06 midterm key word problems

sp06 midterm key word problems - Metabolic Biochemistry j...

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Unformatted text preview: Metabolic Biochemistry j BIBC 102 Midterm Exam 1 Spring 2006 -. (25 points) Fill in g of the enzyme catalyzed reactions which convert glucose to ethanol. 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 reacta and products (eg, ATP, ADP, Pi, NAD+, NADI-I, etc), and any required prosthetic groups (eg, bioti , TPP, etc.) (Note:You do n_ot 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 correche of an intermediate structure if the structure itself is incorrect.) 1' " Glucose ethanol (draw structure) II. (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 MC in'the carboxyl carbon (CH3-C(O)— l4C02) to this mitochondrial suspension, incubate, and then isolate succinate. To your initial surprise, you observe that succinate has a small amOunt of 14C label. 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 HC 1395 te. points) (a) Draw a diagram or me overwew or proton anu Electron circuits 1U umucuouuua aha-lung, th NADH in the matrix and ADP and Pi in the cytosol and ending with the reduction of oxygen to ater and the formation of ATP (the diagram in the lecture handout will receive filll credit). Label each mplex and protein, identify matrix, intermembrane space, and innerniembrane, and indicate the flow of protons and electrons. - _ (b) Indicate on this diagram the relevant electron carriers in each complex of electron transport g {e.g., FeS, cytochrome a3, Cu, FMN, etc.). a *5 ’ ,3/9— 1 (0 may ' aau-' , 4. "‘I-I-u... l {finder h [74. 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 ? 57st fascia I; refwré/ ,4: ream #4 74L Afi-latcrzéic._ aoflr/Sr-LI—vuf/ So 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. _ ' 3CD HTP/ / e o z - M01" ,_/ If f I); 3' .e ______ #3478: I4? 4;} fluxtrobié- " '2 lying/aka" xx - 'r’ ghee—are CoAJJ'am/a I, C‘ What regulatory mechanisms explain how the removal of oxygen increases the rate of glucose consumption? Explain in terms of the action of allosteric effector(s) on specific enzyme (5). Iii/fias/Vlic 0F /L45'/A;C~uc/{ 19/34:)? . 4/42,.) ,, 02 (A remote/l ’45-”; SJ; finp/ fémflrtfr 5,4,.“ AIM a “J six/UAW;- kebab of FFKM/ M/ L.” ILA-J 4/45/97}: fi-dJc GAAAJ7C'J 1:... 9777a; am/ [flirt/f] “Ame flFK. D. What effect does the removal of oxygen have on the rate of C02 generation? By what factor does the rate of CO; generation change? Show your calculations. 5 ' V. (20 points) (A) In the space below, please sketch the V0 versus S plot for an enzyme obeying Michaelis- Menten kinetics at enzyme concentrations of X and 2X. Label the Mo_l_ines,_ and indicate Km and Vmax for_ each of the two enzyme concentrations. '- ' ' / ' k umaxi Rm [£‘J= zx-fl ._ K 1}“ T - i I; h. I . i / :- X _\ [:1 Kiwi. I [62! -—- =- x 6/, (. km; [53 —-2 (B) In the space below, please sketch the ll Weaver burke plot for this enzyme in the presence and absence of a competitive inhibitor. Show the valuesof'each. slope in terms of Km, Vrnax, and Ki _ / ‘—,-. '~ { KM(H~ “3 Kr” (1% 7:"? i ‘ ‘ 9 “any UM r '"' .. . - D 1— unfit in; U” f _ has, 0"] -I’ ._~ ‘1 ll“ hillOi" 6. '48 (C) In the space below, p ease sketch the V0 versus S plot for an enzyme which shows positive cooperativity in substrate binding, in the presence and absence of an allosteric activator; label each line. With reference to this plot, explain how the allosteric activator increases the activity of the enzyme. . -—-":? I a...“ 51-9 a»: 2n, #4.. (D). Consider the reactlon: {SB ' ATP + pyruvate —) phOSphoenol pyruvate + ADP “‘ l 3 Given that the AG‘” for ATP hydrolysis is —30.5 kamol, the AG“ for phosphoenolpyruvate hydrolysis is 451.9 kamol, RT is 2.48 chlmol, and the concentration are: [ATP] = 2.24 leL [ADP] = 025111le, [pyruvate] = 0.051mM, [phosphoenolpymvate] = 0.023 mM, and [phosphate] = SmM, what will the 136' be L. for this reaction? Do not calculate an answer. Full credit will be given for correct set up of the final equation. , AG: AG“ + RT fink ATP ‘9 All? “30.5 KIT/tool Pyruvofie ’9 PliOSPl‘OCDOl WUWfie +'él .Cl kI/mol ' + 31.4 ivJ/mol AG=3lfi +RT£n 'LADPJEPEPJ WE) :3m+(2.4s)£n W) "Q 0'05l .7. all) AG’ ...
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sp06 midterm key word problems - Metabolic Biochemistry j...

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