Researchers have identified a mutant form of sigma factor that binds more tightly to the core polymerase enzyme compared to a normal sigma factor. Would the rate of transcription be faster or slower in cells that carry this mutant sigma factor? Explain why.

The transcription rate will slow down in the cells that carry mutant sigma factor.

Explanation:

Sigma factor play an important role during initiation of transcription. The sigma factor binds to the core RNA polymerase (that contains alpha, beta, beta dash and omega subunit) to form hollow enzyme.

The binding to sigma factor to core RNA polymerase initiates the formation closed promoter complex and the release of sigma factor result in the formation of open promoter complex that signals the ending of transcription initiation.

Now if the sigma factor binds tightly to the core RNA polymerase then it will be difficult for the sigma factor to get dissiciated from hollow enzyme, as a result transcription will remain in the initiation phase. So the process cannot enter the elongation phase.