S07-e2_key

S07-e2_key - EXAM II CH339K Dr Robertus Spring 2007...

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EXAM II CH339K ( Dr. Robertus) Spring 2007 Name:_____________ ANSWER KEY _________________________________ UTEID: ______________________________________________ SHOW WORK FOR ALL COMPUTATIONAL PROBLEMS OR NO CREDIT! 1 cal = 4.18 J and therefore: R= 8.314 J/mole K = 1.99 cal/mole K Avogadro’s number = 6 x 10 23 ; F=96.5 kJ/mol*V = 23.1 Kcal/mol*V Assume T=25 ° C in all problems, unless otherwise stated. Problem values are shown in [x] 1. [4] We want to over express our favorite enzyme, bevoase. Fortunately we have the gene encoding bevoase on a piece of DNA with BamH1 sticky ends. We insert this into the plasmid pBR322 (at right) and transform it into E. coli. How can we identify those transformant colonies that contain the bevoase gene? Inserting the bevoase gene at the BamH1 site Disrupts the tetracycline resistance gene. Therefore, the transformed E. coli will survive when the growth media is supplemented with ampicillin. 2. [6] Difference between G°’ and G. Consider the following interconversion, which occurs in glycolysis. Fructose 6-phosphate glucose 6-phosphate; Keq = 1.97 (a) What is G°’ for the reaction (assuming that the temperature is 25 °C)? G°’ = -RTlnKeq = -5.7log(1.97) = -1.7 KJ/mol

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(b) If the concentration of fructose 6-phosphate is adjusted to 150 mM and that of glucose 6-phosphate is adjusted to 50 mM, what is G? G= G°’ + RTlnKeq = -1.7 KJ/mol + 5.7log(50/150) = -1.7KJ/mol – 2.7 KJ/mol = -4.4 KJ/mol (c) Why are G°’ and G different? These values are different because G°’ is based on a fixed concentrations (1M) and temperature. G is a function of reactant and product concentrations, as well as temperature. 3a. [2] Draw the structure of β -glucose in the pyranose form O OH OH OH CH 2 OH OH 3b. [2] Draw the C4 epimer of β -glucose in the pyranose form. O OH OH CH 2 OH OH OH What is the name of this important sugar? β -galactose
4. 20. [3] Based on what we said in class, sketch the double reciprocal plot for the inhibition kinetics of the cyclooxygenase enzyme (COX) with ibuprofen. Include at least two lines, one without inhibitor, and one with. Label your axis appropriately

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S07-e2_key - EXAM II CH339K Dr Robertus Spring 2007...

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