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 equilibrium constant.
The correct answer and explanation is:
The correct answer is:
Enzymes lower the energy of the transition state for the rate-determining step.
Explanation:
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 barrier that must be overcome for reactants to be transformed into products. Enzymes achieve this by stabilizing the transition state, which is the high-energy intermediate formed during a reaction.
The key feature of enzyme action is their ability to lower the energy of the transition state for the rate-determining step. The rate-determining step is the slowest part of the reaction, and enzymes make this step proceed more efficiently. They do so by binding to the reactants (also called substrates) and positioning them in a way that favors the transition state, thus lowering the activation energy needed.
This process does not affect the overall thermodynamics of the reaction, which means that enzymes do not change the equilibrium position or equilibrium constant. The equilibrium constant depends on the free energies of the reactants and products, and enzymes do not alter these. They only make the reaction reach equilibrium faster by increasing the rate of the reaction in both the forward and reverse directions equally.
To summarize, enzymes primarily influence the reaction rate by lowering the activation energy, especially for the rate-determining step. They do not shift equilibrium, nor do they change the equilibrium constant, which is a key distinction in understanding enzyme function.