Question

Below figure represents the transcription process in prokaryote. Identify A, B, C and D.

• A. A - RNA polymerase; B – RNA; C – ρ factor; D – σ factor
• B. A - ρ factor; B – RNA; C–RNA polymerase; D – σ factor
• C. A - σ factor; B – RNA; C – ρ factor; D – RNA polymerase
• D. A - σ factor; B – RNA; C – RNA polymerase; D – ρ factor

Answer 1

The correct option is C A - σ factor; B – RNA; C – ρ factor; D – RNA polymerase

Sigma (σ) factor is a subunit of RNA polymerase, which binds with RNA polymerase core forming a holoenzyme. This duplex molecule (RNA polymerase + σ factor) together joins with the promoter region of the DNA and is capable of competent initiation of transcription. RNA polymerase is the enzyme responsible for synthesising a RNA sequence during the process of transcription.

RNA polymerase has binding site for Rho factor, when the Rho – RNA couple meet the RNA polymerase, it pulls apart the RNA from DNA thus stopping transcription.