Transcription and RNA Processing · Zoology

In prokaryotes, which subunit of the RNA polymerase holoenzyme is essential for promoter recognition and initiation specificity?

  1. Alpha subunit
  2. Beta subunit
  3. Sigma factor (σ)
  4. Omega subunit
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Correct answer: Sigma factor (σ)

The sigma (σ) factor confers promoter specificity on RNA polymerase, guiding it to bind the -10 and -35 consensus sequences. After transcription initiation and synthesis of a short RNA, the sigma factor is released from the core enzyme.

Difficulty: Medium Question 4 of 20

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