To catalyze a biochemical reaction, an enzyme typically
A. drives the reaction to completion by consuming byproducts of the reaction
B. binds temporarily to reactant molecules to lower the activation energy of the reaction
C. dissociates into additional reactant molecules, thereby increasing the reaction rate
D. decomposes and releases energy to increase the number of successful collisions between reactant molecules
The Correct Answer and Explanation is :
The correct answer is B: binds temporarily to reactant molecules to lower the activation energy of the reaction.
Explanation:
Enzymes are biological catalysts that accelerate chemical reactions without being consumed in the process. They work by binding to substrate molecules (reactants) and lowering the activation energy required for a reaction to occur. The activation energy is the energy barrier that must be overcome for a chemical reaction to proceed. By reducing this barrier, enzymes make it easier for the reaction to occur and increase the reaction rate.
Here’s a breakdown of the process:
- Enzyme-Substrate Binding: The enzyme binds to its substrate (reactant) at a specific region known as the active site. This binding is typically highly specific, meaning that each enzyme only catalyzes certain reactions based on the shape and chemical properties of the active site.
- Lowering Activation Energy: Once the enzyme is bound to the substrate, it stabilizes the transition state of the reaction, lowering the energy required to convert reactants into products. This allows the reaction to proceed more quickly at lower temperatures, which is particularly beneficial in biological systems where conditions may not be optimal for spontaneous reactions.
- Release of Products: After the reaction occurs, the enzyme releases the products and is free to catalyze another reaction. Importantly, enzymes are not consumed during the reaction, so they can be used repeatedly.
Why the other choices are incorrect:
- A: Enzymes do not drive reactions to completion by consuming byproducts. Their role is to speed up the reaction by lowering activation energy.
- C: Enzymes do not dissociate into additional reactants. They facilitate reactions by lowering activation energy.
- D: Enzymes do not decompose to release energy. Instead, they lower the activation energy by providing an alternative reaction pathway.
In summary, enzymes function by temporarily binding to substrates and reducing the activation energy of biochemical reactions, which enhances the efficiency of cellular processes.