A Level Biology Practice Exam

What characterizes an enzyme-substrate complex?

1. Formation of a new enzyme

2. Binding of a product to the active site

3. Interaction between enzyme and substrate

4. Release of energy during reaction

The correct answer is: Interaction between enzyme and substrate

An enzyme-substrate complex is characterized by the interaction between the enzyme and the substrate. This complex forms when the substrate binds to the enzyme's active site, leading to a series of chemical reactions that transform the substrate into products. The specific shape and chemical properties of the active site allow the enzyme to recognize and bind to the substrate, which is a crucial step in the enzymatic reaction process. This interaction is pivotal because it not only facilitates the conversion of substrates into products but also lowers the activation energy required for the reaction to proceed, thereby increasing the reaction rate. The stabilization of the transition state within the enzyme-substrate complex is essential for efficient catalysis. Understanding this concept helps elucidate how enzymes function and their roles in biological processes, including metabolism and cellular signaling.