If the repressor of an inducible operon were mutated so it could not bind the operator, the operon would be transcribed continuously , regardless of whether the inducer is present or not.

Quick Scoop

In a normal inducible operon (like the lac operon), the default state is “off” because the active repressor sits on the operator and blocks RNA polymerase.

When an inducer binds the repressor, it changes shape and falls off the operator, so transcription turns “on.”

If a mutation prevents the repressor from binding the operator at all:

  • The operator is never blocked.
  • RNA polymerase can bind the promoter and transcribe the structural genes all the time.
  • The result is constitutive (continuous) expression of the operon’s genes, independent of inducer or substrate levels.

So, among typical multiple‑choice options, the correct outcome is:

Continuous transcription of the operon’s genes.

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