midterm_2004

midterm_2004 - page1 (of10) BIBC102 Midterm 1 Fa 2004 Name_...

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page1 (of10) Name____________________________________ BIBC102 Midterm 1 Fa 2004 Stu. ID#__________________________________ B C A Reaction Energetics and Catalysis (8 points) This picture is an energy diagram for the molecule S being converted into the molecule P. The vertical axis is free energy, and the horizontal axis is the progress of the reaction. Several free energy changes are represented on the curve, as ± G A, B or C. For questions 1-5 Choose a given labeled free energy change or a function of those on the graph (eg A, B+A, C-A, whatever), to express the requested quantity. Each ± G is in the graph is a positive number. 1) What is the free energy change for S becoming P? write here: 2) What is the free energy change for P becoming S? write here : 3) What is the activation energy for the S to P reaction? write here: 4) What is the activation energy for the P to S reaction? write here: 5) What is the component of the activation energy for the P to S reaction that can not write here: be affected by an enzyme? 6) Consider an enzyme that catalyzes the S to P reaction. Sketch in a little curve on the same axis that shows the effect of such an enzyme 7) Does the enzymes also catalyze the P to S reaction? Why do you say this? 8) Suppose the enzyme lowers the activation energy by 7kJ/mole. What is the activation energy for the P to S reaction when the enzyme is added? write letter here: ____________ a) 7 kJ/mole c) (A-7)kJ/mole b) (C-7)kJ/mole d) (A+C-7) kJ/mole e) no change f) correct choice not shown
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page2 (of10) Name____________________________________ BIBC102 Midterm 1 Fa 2004 Stu. ID#__________________________________ The Enzyme Apprentice (9 points) Wallace and Grommet are each trying to get a job at Bongo Pharmaceuticals. Because many drug targets are enzymes, the people at Bongo decide to test their skills as enzymologists. . Each is given a lab for the afternoon, and each is told to measure the activity of the same batch of purified enzyme. The day passes and at 5 pm, Wallace and Grommet present their data. Both report that the enzyme has Michelis-Menten behavior. They each have found the Km to be the same, 0.2mM. However, Wallace has a Vmax of 4 x 10 4 moles per second, and Grommet has a Vmax value of 8 x 10 4 moles per second. 9) What is the substrate concentration that will give half-maximal rate according to Wallace? ans:___________ 10) Is the substrate concentration that causes the half-maximal rate in Grommet's experiments the same or different? Why? 11) What is the substrate concentration that will cause 2/3 the maximal rate according to Wallace? (hint: you do NOT need to use any Vmax to calculate this…) ans:___________ 12 (4 pts)) Using the axis to the right, sketch the data obtained by Wallace and Grommet as a Lineweaver-Burk plot. I don’t care about the actual numbers, just the comparison of the two data sets. Sketch graphs, label the axes and the intercepts. Indicte which plot is which with a W and a G.
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midterm_2004 - page1 (of10) BIBC102 Midterm 1 Fa 2004 Name_...

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