RNA Online A comprehensive package for the hands-on teaching of Molecular Biology. Changed the image and checked the links. DNA is a long chain of bases, as shown elsewhere . These other factors may be proteins or other kinds of molecules. First Steps Transcription of DNA into RNA is different in prokaryotes , and in eukaryotes .
Bacteria are prokaryotes.
The RNA polymerase has a natural affinity for DNA, and will fix itself to DNA, and start polymerization. If the RNA polymerase attaches to any DNA sequence, it will soon detach, and the tiny RNA generated by the polymerase will be hydrolysed. Another hypothesis is that the factor sigma attaches to RNApol anyway and the enzyme is then able to slide along the DNA until it finds a promoter. After some nucleotides have been added, the factor 'sigma' detaches, and can be reused for starting more RNA synthesis. Stop signals in the DNA indicate the end of the gene to be transcribed.