Question

(6 pts.) Make a diagram of the prokaryotic initiation of transcription - include the +1 start site, the -10 and the -35 sites and RNA polymerase plus sigma factor.

Answer 1

And her here Begin hare Coding Strand I 31 New RNA template strand Initiation PE 31 RNAPTITIS Rho factor Termination an Signa factor PE 31 PE 모 5 5 S1 3 TIS. TIS. Elongation s New RNA New RNA

Promotele element PE s' TGTT GACA TATARI - H -35 bp -10bb th! tai T1 TIS Termination point Cene 2 5) ام Neue RNA.

The process of RNA synthesis in bacteria begins with the binding of RNA polymerase molecule on the DNA. RNA polymeraserecognises the transcription start site on the template strand of DNA with the help of certain specific regions on the DNA known as promoter elements. The sigma factor of RNA polymerase is especially crucial in recognises the promoter elements. There are two promoter elements regions identified in DNA:-

1. Pribnow box:-. TATA box. this component is a sequence of 6 nucleotide bases that occurs 10 base pairs upstream to the transcription initiation point. this region of highly conserved nucleotide bases of A-T rich sequence plays a major role in recognises the transcription initiation site (TIS) by RNAP and thereby initiating the process of transcription.
2. -35 sequence:- the second component of a promoter elements with a consensus sequence of 8 nucleotide bases occurs 35 base pairs upstream to the TIS.

Soon after the binding of RNAP to the promoter element, the first nucleotide always a purine is inserted at the 5' end of the nascent RNA molecule and the RNAP moves next to the second base in the template. A phosphodiester bond forms with the second nucleotide base and the transcription is initiated. At this stage, the sigma factor of RNAP dissociates from the rest of the enzyme.