RNA polymerase catalyzes RNA synthesis. To transcribe a gene, RNA polymerase proceeds through a series of well-defined steps, which are grouped into three phases: initiation, elongation and termination.
(i) Initiation : RNA polymerase binds with the promoter region of the DNA. The Promoter - polymerase complex undergoes structural changes required for transcription.
(ii) Elongation : During elongation, RNA polymerase unwinds the DNA in front and re-anneals it behind; it dissociates the growing RNA chain from the template as it moves along. It also performs proofreading function.
(iii) Termination: Once the polymerase has transcribed the length of the gene, it stops and release the RNA product.
