[Campbell Biology P.204] Based on Figure 8.15 and the accompanying text, which statement bes... | Practice Question

Based on Figure 8.15 and the accompanying text, which statement best describes the "induced fit" model of enzyme-substrate interaction?

  • A: The enzyme's active site is a rigid, pre-formed structure that exactly fits only one specific substrate, like a lock and key.
  • B: When a substrate binds to the active site, the enzyme undergoes a slight conformational change, allowing for stronger binding and optimal catalysis.
  • C: The substrate changes its shape to perfectly match the enzyme's rigid active site upon binding.
  • D: Enzymes constantly "dance" between all possible shapes, and only the shape with the lowest free energy can bind the substrate effectively.

Explanation

The text states that enzymes are not rigid and that when the substrate enters the active site, 'it forms weak bonds with the enzyme, inducing a change in the shape of the protein. This change allows additional weak bonds to form, causing the active site to enfold the substrate and hold it in place.' This accurately describes the induced fit model, where the enzyme's shape is dynamic and molds around the substrate for optimal interaction.