Question

QUESTION 19 Which of the following subunits plays no role in chain elongation during transcription? O a) RNA polymerase holoenzyme O b) sigma factor O c) RNA polymerase core enzyme O d) all of the above O e) none of the above

Answer 1

Ans. The correct option is b). sigma factor.

Sigma factor is the one that binds to the RNA polymerase core enzyme and initiates the transcription, so it is only necessary for initiation of transcription and has no role in chain elongation during transcription.

All other options are incorrect:

a) RNA polymerase holoenzyme consist of sigma factor and RNA polymerase core enzyme. RNA polymerase holoenzyme is necessary for initiation of transcription, once the initiation is achieved sigma factor dissociates and the elongation is done by the core enzyme.

c). RNA polymerase core enzyme is the one that is involved in elongation during transcription.

d). all of the above is incorrect as only b) sigma factor is the correct option

e). none of the above is incorrect as one of them i.e. b). sigma factor is the correct option.