Which of the following statements about enzymes is true?
Multiple Choice
Enzymes lower the energy of the transition state for the rate-determining step.
Enzymes Increase the activation energy for a reaction.
Enzymes shift the equilibrium to favor the product.
Enzymes decrease the equlilibrium constant.
The correct answer and explanation is:
The correct statement is:
Enzymes lower the energy of the transition state for the rate-determining step.
Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur. The activation energy is the energy needed to reach the transition state, the highest energy point during a reaction. Enzymes achieve this by providing an alternative reaction pathway with a lower activation energy.
Enzymes do not change the equilibrium position of the reaction. The equilibrium constant (K) of a reaction is determined by the free energy difference between the reactants and products, which is unaffected by the presence of an enzyme. Enzymes only speed up the rate at which equilibrium is reached but do not alter the equilibrium itself. This means that while enzymes facilitate reactions, they do not “shift” the equilibrium toward either reactants or products.
The role of enzymes is to make the reaction occur more quickly by lowering the energy barrier. They achieve this by binding to reactant molecules (substrates) and stabilizing the transition state, which decreases the energy required for the reaction to proceed. Importantly, enzymes are not consumed in the reaction. After the reaction is complete, the products are released, and the enzyme can participate in another reaction cycle.
In summary, enzymes function by lowering the activation energy, facilitating the transition to the products more efficiently. They do not alter the overall energy change of the reaction nor the equilibrium constant, but their presence allows reactions to occur faster under physiological conditions.