Problem

For parts (a) and (b) of this problem use the following standard reduction potentials, fre...

For parts (a) and (b) of this problem use the following standard reduction potentials, free energies, and nonequilibrium concentrations of reactants and products:

ATP = 3.10 mM

Pi = 5.90 mM

ADP = 220 μM

glucose = 5.10 mM

pyruvate = 62.0 μM

NAD+ = 350 μM

NADH = 15.0μM

CO2 = 15.0 torr

half reaction	E0’ (V)
NAD+ + H+ + 2e−→NADH	−0.315
2Pyruvate + 6H+ + 4e− → glucose	−0.590

pyruvate + NADH + 2H+ → ethanol + NAD+ + CO2 AG°′ = −64.4kJ/mol

ATP + H2O → ADP + Pi + H+ ΔG°′ = −30.5kJ/mol

(a) Consider the last two steps in the alcoholic fermentation of glucose by brewer’s yeast:
Calculate the nonequilibrium concentration of ethanol in yeast cells, if ΔG = −38.3 kJ/mol for this reaction at pH = 7.4 and 37 °C when the reactants and products are at the concentrations given above.
(b) Consider the degradation of glucose to pyruvate by the glycolytic pathway:
Calculate ΔG for this reaction at pH = 7.4 and 37 °C.