Which statement best describes basal transcription factors?

Which statement best describes basal transcription factors?

• A. They are essential for transcription, and cannot increase the rate of transcription by themselves.
• B. They can increase the rate of transcription by themselves.
• C. They are not involved in transcription.
• D. They are only required in prokaryotes.

Answer: (A)

Basal transcription factors are general proteins that help RNA polymerase II start transcription at gene promoters. They come together at the promoter to form the preinitiation complex, which is essential for transcription to begin. Because of their role, transcription can occur at a basic, minimal level even without additional regulatory inputs, so they set the baseline—the essential ingredient for transcription to happen. However, by themselves they don’t push transcription to higher levels. Increasing transcription requires activator proteins and other cofactors that bind to enhancers or promoter elements and recruit additional machinery or modify chromatin to boost transcription above the basal rate. So the statement that these factors are essential for transcription and cannot increase the rate of transcription by themselves is the correct one. It’s also worth noting they’re part of eukaryotic transcription; prokaryotes regulate transcription differently, using sigma factors rather than these basal transcription factors.

Basal transcription factors are general proteins that help RNA polymerase II start transcription at gene promoters. They come together at the promoter to form the preinitiation complex, which is essential for transcription to begin. Because of their role, transcription can occur at a basic, minimal level even without additional regulatory inputs, so they set the baseline—the essential ingredient for transcription to happen.

However, by themselves they don’t push transcription to higher levels. Increasing transcription requires activator proteins and other cofactors that bind to enhancers or promoter elements and recruit additional machinery or modify chromatin to boost transcription above the basal rate. So the statement that these factors are essential for transcription and cannot increase the rate of transcription by themselves is the correct one. It’s also worth noting they’re part of eukaryotic transcription; prokaryotes regulate transcription differently, using sigma factors rather than these basal transcription factors.