Question

The RNA polymerase holoenzyme transcribes

• A. the promoter, structural gene and the terminator region
• B. the promoter and the terminator region
• C. the structural gene and the terminator region
• D. the structural gene only

Answer 1

The correct option is D the structural gene only

RNA polymerase enzyme is a holoenzyme having 2 alpha, 1 beta, 1 beta’, 1 omega subunits and 1 sigma factor that catalyses the transcription process.

Transcription is the process of copying genetic information from one strand of the DNA (template strand) into RNA.

The segment of DNA which takes part in transcription is the transcription unit. It consists of a promoter, the structural gene and a terminator.

Transcription occurs in three steps: initiation, elongation and termination.

For initiation of transcription, the sigma factor of RNA polymerase is required and for termination the rho factor encounters the RNA polymerase.

The promoter and terminator regions are useful for initiating and terminating the transcription process only. They do not get transcribed into RNA.

Only the structural gene that is situated between promoter and terminator regions of the transcription unit gets transcribed into RNA.

Therefore, only structural genes are transcribed into RNA by the RNA polymerase enzyme.