NEET · BiologyHard
In the lac operon, if a mutation occurs in the operator region such that the repressor protein can no longer bind, what will be the phenotype of the cell regarding -galactosidase production?
- A.Constitutive expression
- B.Inducible expression
- C.No expression
- D.Repressed expression
Show correct answer & step-by-step solution
Correct answer: A — Constitutive expression
Solution
- The operator is the binding site for the lac repressor.
- Binding of the repressor prevents RNA polymerase from transcribing the structural genes.
- If the repressor cannot bind, the operator is permanently 'open'.
- RNA polymerase can bind to the promoter and transcribe the genes regardless of lactose presence.
- This results in constitutive expression.
- Hence the answer is (A).
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