Which factor is important for termination of transcription? 

The correct answer is ρ (Rho)

Explanation:

• Transcription is the process by which a DNA sequence is copied into RNA. It is carried out by RNA polymerase and includes three main stages: initiation, elongation, and termination.
  • Initiation: In this stage, RNA polymerase binds to the promoter region of the DNA, forming a transcription initiation complex. In prokaryotes, this process often involves the transient association of a sigma factor (σ) with the RNA polymerase core enzyme, which helps in recognizing and binding to the promoter sequence.
  • Elongation: Once the initiation complex is formed, RNA polymerase begins moving along the DNA template, synthesizing RNA in the 5' to 3' direction. During elongation, RNA polymerase does not require the transient association of initiation or termination factors. It simply catalyzes the addition of ribonucleotides to the growing RNA chain based on the complementary base pairing with the DNA template.
  • Termination: In the termination stage, RNA polymerase recognizes specific sequences in the DNA template that signal the end of the gene or transcription unit. In prokaryotes, termination often involves the transient association of a termination factor (ρ) with the RNA polymerase complex, leading to the release of the newly synthesized RNA molecule and dissociation of RNA polymerase from the DNA template.

Other Options:

• α (Alpha): Alpha subunits are part of the core RNA polymerase enzyme complex and are involved in the assembly and stability of RNA polymerase. They play a role in initiating transcription but are not involved in termination.
• σ (Sigma): Sigma factors are essential for the initiation of transcription. They help RNA polymerase recognize and bind to specific promoter sequences but dissociate from RNA polymerase after initiation. Sigma factors are not involved in transcription termination.
• γ (Gamma): Gamma is not a factor associated with transcription in prokaryotes.