CHEM153A_midterm2_W09_answers

CHEM153A_midterm2_W09_answers - (pO 2 = 80 torr, = 0.27)...

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Chem 153A, Winter 2009 Midterm Exam 2 Answers 1/2 Practice Midterm 2 Answer Key Page 2 2. a. False b. True c. True d. True e. False 3. c. 4. a. 2, 6 b. 1, 2, 3, 4 c. 3, 4 d. 1, 4 Page 4 5. a. & f. b. x-int = 1/-K m K m = -1/x-int = -1mM/-0.25 = 4 mM c. y-int = 1/V max V max = 1/y-int = 1s/0.2μM = 5 μM/s d. k cat = V max /[E] = 5 µM/s / 0.0008 µM = 6250 s -1 e. cat. eff. = k cat /K m = 6250 s -1 / 4 mM = 1562.5 s -1 mM -1 g. competitive h. K' m = αK m , or, α = K' m /K m also, α = 1 + [I]/K I or, K I = [I]/(α - 1) = [I]/{(K' m /K m )-1} = 5mM/{(20mM/4mM)-1} = 1.25 mM i. frigidol (K I for frigidol is lower than K m for caterpillic acid) Page 5 6. a. lysozyme b. peptidoglycan; bacterial cell wall structure c. hydrolase d. proximity & orientation (nucleophilic) covalent catalysis general acid catalysis preferential binding of transition state general base catalysis Page 6 7. a. 4 b. 3 c. 1 d. 5 8. heme iron, distal His 9. for flipperglobin (F): hyperbolic curve , passing through the point (pO 2 = 20 torr, θ = 0.5), and approaching θ =1.0 for goglobin (G): sigmoidal curve, passing through the points
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Unformatted text preview: (pO 2 = 80 torr, = 0.27) and (pO 2 = 200 torr, = 0.9), and approaching =1.0 M M+F 1/V o (s/M) 1.0 0.8 0.6 0.4 0.2 1.0 0.75 0.5 0.25 -0.25 0.0 1/[S] (mM-1 ) Chem 153A, Winter 2009 Midterm Exam 2 Answers 2/2 Page 7 10. G' = -RT lnK eq so K eq = e -G'/RT = e (4.9 kJ/mol)/(0.00831 kJ/molK)(310K) = 0.149 to have negative G, [Y]/[X] < K eq , so [Y] < K eq [X] = 0.149(100 M) or [Y] < 14.9 M 11. G = 7.1 kJ/mol + RT ln([Z] 2 /[X]) 12. a. nucleophile or electrophile (either or both OK) b. nucleophile: oxyanions are nucleophilic electrophile: phosphorus carries a partial positive charge & is electrophilic c. Resonance: there is greater resonance stabilization of P i versus the bound phosphate 13. energy charge = 0.5 ( [ADP] + 2[ATP] ) / ( [AMP] + [ADP] + [ATP] ) = 0.5 ( 0.2 + 2(0.7) )/1.0 = 0.8 Extra Credit 1. U, F ATP ADP 2. L, C NADPH + H + NADP + 3. I, S...
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CHEM153A_midterm2_W09_answers - (pO 2 = 80 torr, = 0.27)...

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