In muscle cells,following reaction proceeds as written, i.e.,from left to right. conc of FAD,thermodynamic...

Question

In muscle cells, the following reaction proceeds as written, i.e.,from left to right. How can this occur?

succinate FAD <—> fumarate FADH2 ΔG° = 0.4 kJ/mol

a) It is thermodynamically favored under standard conditions.

b) The concentration of FAD must be higher than FADH2 for this

reaction to occur in the cell.

c) The concentration of fumarate must be higher than succinate for this reaction to occur in the cell.

d) All of the above explain this event

Answer 1

since standard free energy for this reaction and it&#039;s direction is about to zero and slightly possitive , we may not consider it as a thermodynamically favored reaction at standard condition, specially to right.

if you consider the following equation :

dG&#039;(upon concentration condition) = dG&#039;(standard) + RT Ln ([f] * [FADH2]) / ([s] * [FAD]) ; if you increase FAD to FADH2 ratio you will probably drive the reaction to right because you make the free energy of reaction more negative.

so b is correct!