Question

The following statements are the steps in the catalytic action of an enzyme. Arrange them in correct sequence.
a) The active site of the enzyme, now in close proximity of the substrate, breaks the chemical bonds of the substrate and the new enzyme product complex is formed.
b) The substrate binds tightly to the enzyme, inducing a change in the active site of the enzyme.
c) The enzyme releases the products of the reaction and the free enzyme is ready to bind to another molecule of the substrate.
d) The substrate binds to the active site of the enzyme.

• A. c, a, b, d
• B. d, b, a, c
• C. a, b, c, d
• D. d, c, b, a

Hint:

Always start with substrate binding to the active site and end with product release. This simple logic narrows down the options immediately.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept: The catalytic cycle of an enzyme action follows a specific sequential pathway described by the induced-fit model.
Step 2: Key Formula or Approach: Map the biological events from initial contact (substrate binding) to final release (product separation) in a chronological order.
Step 3: Detailed Explanation: The first step is the binding of the substrate to the active site of the enzyme (statement d).
This binding induces a conformational change in the enzyme, making it fit more tightly around the substrate (statement b).
The active site, now in close proximity to the substrate, breaks the chemical bonds of the substrate to form the enzyme-product complex (statement a).
Finally, the enzyme releases the products of the reaction, and the free enzyme is ready to bind to another substrate molecule (statement c).
Thus, the correct sequence is d $\rightarrow$ b $\rightarrow$ a $\rightarrow$ c.
Step 4: Final Answer: The correct sequence matches option (2).