Question

What are the three defined steps of RNAP initiation in Prokaryotes?

Answer 1

The three steps of RNAP initiation in prokaryotes are promoter recognition, DNA unwinding to form an open complex, and chain initiation where RNA synthesis starts. Unlike eukaryotes, no enhancers and transcription factors are involved, and the absence of histones affects DNA strand separation.

Step-by-step explanation:

The initiation of transcription by RNA polymerase (RNAP) in prokaryotes involves three defined steps:

1. Promoter recognition: RNA polymerase binds to the promoter region of the DNA, with the help of sigma factors, to form a closed complex.
2. DNA unwinding: The DNA strands separate to form an open complex, allowing the template strand to be accessed by the RNA polymerase.
3. Chain initiation: RNA polymerase starts synthesizing RNA by adding nucleotides to the 3' end of the growing RNA chain, using the DNA template for guidance.

Unlike in eukaryotes, prokaryotic transcription does not involve enhancers and transcription factors. Additionally, the absence of histones in prokaryotes affects the DNA separation process. After initiation, the RNA polymerase elongates the RNA strand and eventually terminates transcription upon reaching a terminator sequence.