Final answer:
The initiation of transcription in prokaryotes requires RNA polymerase to bind to the promoter region on the DNA. Sigma factors assist in starting transcription at the right site. This can lead to polycistronic mRNAs that encode multiple proteins.
Step-by-step explanation:
The initiation of transcription in prokaryotes begins when the enzyme RNA polymerase binds to a specific sequence on the DNA called the promoter.
This process is aided by proteins known as sigma factors (σ factors) which help the RNA polymerase identify the correct starting point.
Once the RNA polymerase binds to the promoter, it unwinds a small portion of the DNA helix to allow transcription to begin.
As transcription proceeds, the RNA polymerase moves along the DNA, synthesizing a complementary RNA strand.
The prokaryotic cell's lack of a membrane-bound nucleus allows simultaneous transcription and translation.
The DNA in prokaryotes is compact and can result in polycistronic mRNAs, which means a single mRNA may encode multiple proteins.
Different sigma factors are associated with the transcription of different genes, reflecting regulatory mechanisms that ensure specific gene expression as needed by the cell.