Which statement describes the induced-fit model of enzyme action?
Answer and explanation
Correct answer: B. The active site changes shape slightly as the substrate binds
- Step 1: In the induced-fit model, the active site is flexible.
- Step 2: Binding of the substrate changes the shape of the site so that it fits more tightly, which helps lower the activation energy.
Answer
The active site changes shape slightly as the substrate binds.
Why not the others: The active site is rigid and matches the substrate exactly, like a lock and key: describes the lock-and-key model. The substrate changes shape to fit the active site before it binds: it is the enzyme's active site that adjusts. The enzyme changes shape permanently once it has bound one substrate: the enzyme returns to its original shape and is reused.
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