IGNOU BBCCT 123 2026 - Describe the structure and function of prokaryotic RNA polym

Question

Describe the structure and function of prokaryotic RNA polymerase and the role of the sigma factor in transcription initiation.

10 Feb 2026

Answer :

Word Count : 250

Prokaryotic RNA polymerase is a multi-subunit enzyme responsible for synthesizing RNA from a DNA template during transcription. The core enzyme consists of five subunits: two alpha (α) subunits, one beta (β) subunit, one beta prime (β') subunit, and one omega (ω) subunit. These subunits are responsible for the catalytic activity of RNA polymerase and the structural integrity required for the enzyme's function. However, the core enzyme alone cannot initiate transcription efficiently. The sigma (σ) factor is essential for the initiation process. The sigma factor associates with the core enzyme to form the holoenzyme,

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