bibc102COLEMANexam2key - BIBC 102 Fall Quarter 2007 Exam 2...

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BIBC 102 KEY Fall Quarter 2007 Exam 2 (290 points) PID_______________________ 1) (15 pts.) In muscle cells, phosphorylation of ADP from creatine phosphate is a rapid way to restore ATP levels. The standard free energy of hydrolysis for ATP is –30.5 kJ/mol, and the standard free energy of hydrolysis for creatine phosphate is –43.0 kJ/mol. Write the balanced chemical equation for the transfer of phosphate from creatine phosphate to ADP, and calculate the standard free energy change for this reaction. (You don’t need structures here.) creatine phosphate + ADP creatine + ATP (5 pts.) Standard free energy changes are additive: (-43 kJ/mol) + (+30.5 kJ/mol*) = -12.5 kJ/mol (10 pts.) *pos. 30.5 kJ/mol required for addition of phosphate. 2) In reaction 8 of glycolysis, 3-phosphoglycerate is converted to 2-phosphoglycerate. a. (20 pts.) Write a chemical equation for this reaction, showing the complete structures (including structure of the phosphate group) for both compounds. b. (4 pts.) What enzyme catalyzes this reaction? Phosphoglycerate mutase c. (10 pts.) The standard free energy change for the reaction is +4.4 kJ/mol. Using the equation G’° = -RTlnK’ eq where the gas constant is 8.315 J/mol•K, and the temperature is 298 K, calculate the equilibrium constant for this reaction. 4.4 kJ/mol = -(8.315 J/mol·K)(298 K)lnK eq 4400 J/mol = -(8.315 J/mol·K)(298 K)lnK eq lnK eq = 4400 J/mol -(8.315 J/mol·K)(298 K) lnK eq = -1.78 K eq = 0.17 O- O O- P O- O- O-
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2) continued from previous page d. (4 pts.) Does equilibrium for this reaction lie on the reactant (left) side, or product (right) side of the equation? Equilibrium lies on the reactant (left) side. e. (8 pts.) Does this mean that the catalyzed reaction does not proceed spontaneously under cellular conditions? Explain why? No, this reaction does proceed spontaneously, under cellular conditions (4 pts) . G’° and K eq are relatively close to zero and one, respectively, (or) therefore reactant and product concentrations will determine whether the reaction proceeds, and which way it proceeds (4 pts) .
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This note was uploaded on 12/30/2010 for the course BIOLOGY BIBC 102 taught by Professor Scheffler during the Spring '10 term at CSU Northridge.

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bibc102COLEMANexam2key - BIBC 102 Fall Quarter 2007 Exam 2...

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