Enzyme Catalysis & Product Formation — NEET Biology

Correct answer: A — R → S → T → P → Q

The core concept is the catalytic cycle of enzyme action, describing the sequence of events from substrate binding to product release. Let's arrange the given steps according to NCERT Section 9.8.3, 'Nature of Enzyme Action': 1. "First, the substrate binds to the active site of the enzyme, fitting into the active site." This corresponds to R. 2. "The binding of the substrate induces the enzyme to alter its shape, fitting more tightly around the substrate." This describes the induced fit, corresponding to S. 3. "During the state where substrate is bound to the enzyme active site, a new structure of the substrate called transition state structure is formed." This describes the formation of the transition state, corresponding to T. 4. "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." This describes the formation of the enzyme-product complex, corresponding to P. 5. "The enzyme releases the products of the reaction and the free enzyme is ready to bind to another molecule of the substrate and run through the catalytic cycle once again." This describes product release and enzyme regeneration, corresponding to Q. Thus, the correct sequence is R → S → T → P → Q. The final answer is A, as it presents the correct sequential order of events in the enzyme's catalytic cycle. Concept Recap: The enzyme catalytic cycle involves sequential steps: substrate binding at the active site, induced fit causing tighter binding, formation of a transition state, conversion to an enzyme-product complex, and finally, product release with enzyme regeneration.