Question

Which of the following statements concerning the thermodynamics of biochemical reactions are true? Briefly explain why each statement is true or false. i. Enzymes exploit Le Chatelier's principle to decrease ΔG xn, making a reaction more favorable. ii. Most enzyme-catalyzed reactions that couple unfavorable reactions with ATP hydrolysis proceed via a different pathway compared to the uncatalyzed reaction. iii. Enzymes lower ΔG ∘ mon by increasing Keq ​of a reaction. iv. Many cellular reactions essential to life are nonspontaneous and require enzymes to couple them with favorable reactions.

Answer 1

Enzymes lower activation energy, allowing reactions to occur more readily but do not change the overall energy change or equilibrium constant. Many cellular reactions require enzymes to couple them with favourable outcomes, following unique pathways that differ from uncatalyzed reactions.

Step-by-step explanation:

i. False. Enzymes do not exploit Le Chatelier's principle to decrease ΔG xn. Instead, they lower the activation energy required for the reaction to proceed, increasing the rate at which the reaction occurs, but do not affect the overall energy change (ΔG) of the reaction.

ii. True. Many enzyme-catalyzed reactions that pair unfavourable reactions with ATP hydrolysis do indeed follow a different route compared to the uncatalyzed reaction. This is because the enzyme provides a unique environment for the reaction to occur, forming an enzyme-substrate complex that allows the reaction to proceed more readily.

iii. False. Enzymes don't increase the equilibrium constant (Keq) of a reaction. They simply quicken the rate by which equilibrium is achieved by reducing the activation energy required for the reaction.

iv. True. A significant number of cellular reactions crucial for life are nonspontaneous and require enzymes to couple them with favourable reactions. The enzyme's role in these reactions is typically to lower the activation energy, facilitating the reaction to go forward even if it's not spontaneously favourable.

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