In muscle cells, the following reaction proceeds as written, i.e. , from left to right, despite having Δ G ° ' ≈ +30 kJ\mol. How can this occur? Malate + NAD⁺ → oxaloacetate + NADH + H⁺ A) It is obviously thermodynamically favored under standard conditions. B) In the cell, it is kinetically favored, even though it's thermodynamically unfavored. C) The concentration of malate must be higher than oxaloacetate for this reaction to occur in the cell. D) [H⁺] must be higher in muscle than under standard conditions, thus altering Δ G ° ' to Δ G ° .

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DThe reaction proceeds from left to right despite being thermodynamically unfavored under standard conditions due to cellular conditions that differ from standard conditions. The concentration of reactants and products in the cell can shift the equilibrium of the reaction (choice C). Additionally, the concentration of hydrogen ions ([H+]), which can affect the pH and thus the Gibbs free energy of the reaction, can also be different in muscle cells compared to standard conditions, altering the effective ΔG of the reaction (choice D).

In Muscle Cells, the Following Reaction Proceeds as Written, I