Apentix/AP Biology/Unit 1: Chemistry of Life/Question
AP Biologyeasymcq1 pt

According to the induced fit model, what happens when a substrate enters an enzyme's active site?

A.The rigid active site ejects any molecule whose size differs slightly from the natural substrate.
B.The substrate is immediately hydrolyzed by water held permanently inside the site.
C.The enzyme changes shape permanently and becomes a different enzyme afterward.
D.The active site adjusts its shape around the substrate, and these new contacts stabilize the transition state.

Explanation

Core Concept

Induced fit describes mutual molding of enzyme and substrate after initial binding. Side chains within the active site shift to grip the bound molecule tightly, positioning reactive groups and often straining particular bonds toward their transition-state geometry. These contacts lower the energy of the transition state, which lowers the activation barrier and accelerates the reaction. After catalysis the products no longer fit snugly and diffuse away, letting the site reopen for the next substrate.

Correct Answer

DThe active site adjusts its shape around the substrate, and these new contacts stabilize the transition state.

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