Question

In bacterial operons, which mutation would prevent transcription of downstream structural genes but not affect the promoter region?

• A. Mutation in the operator
• B. Mutation in the promoter
• C. Mutation in the repressor gene
• D. Mutation in the Shine-Dalgarno sequence

Hint:

Mutations in the operator region of an operon can disrupt transcription by preventing the repressor from binding.

Answer 1

The Correct Option is A

A mutation in the operator region would prevent transcription of downstream structural genes by preventing the repressor from binding, thus inhibiting the transcription initiation process. The promoter, repressor gene, and Shine-Dalgarno sequence are involved in gene regulation and translation, but the operator is key to controlling transcription.