Now that we’ve considered some of the major components of transcription, we’re ready to take a detailed look at the process. Transcription can be conveniently divided into three stages:
Initiation, in which the transcription apparatus assembles on the promoter and begins the synthesis of RNA
Elongation, in which DNA is threaded through RNA polymerase, and the polymerase unwinds the DNA and adds new nucleotides, one at a time, to the 3′ end of the growing RNA strand
Termination, the recognition of the end of the transcription unit and the separation of the RNA molecule from the DNA template
We will examine each of these steps in bacterial cells, in which the process is best understood.