Question

Mutations in which of the following elements would abrogate RNA polymerase's ability to activate gene expression?

A. regulatory DNA sequence region

B. promoter

C. transcription termination site

D. major groove

Answer 1

Mutations in the promoter, specifically in areas like the TATA box, would prevent RNA polymerase from binding and initiating transcription, thus abrogating gene expression. The correct option is B. promoter

Step-by-step explanation:

Mutations in the promoter of a gene can significantly affect the ability of RNA polymerase to activate gene expression. The promoter contains critical DNA sequences, such as the TATA box, which play a crucial role in the initiation of transcription. Transcription factors bind to these sequences, allowing RNA polymerase to properly align and begin the transcription process. Therefore, if there were mutations in the promoter sequence, particularly in the TATA box or other critical regions such as the GC box and CAT box, it would lead to the inability of RNA polymerase to bind. This would effectively abrogate gene expression as transcription could not be initiated.

On the other hand, mutations in the regulatory DNA sequence region, transcription termination site, or alterations affecting the major groove would not directly prevent RNA polymerase from initiating transcription, although they might affect other aspects of gene regulation. The correct option is B. promoter