The process of copying genetic information from one strand of the DNA into RNA is termed as transcription. In bacteria, there are three major types of RNAs: mRNA (messenger RNA), tRNA (transfer RNA) and rRNA (ribosomal RNA). All three RNAs are needed to synthesise a protein in a cell. The mRNA provides the template, tRNA brings amino acids and reads the genetic code and rRNAs play structural and catalytic role during translation. There is single DNA-dependent RNA polymerase that catalyses transcription of all types of RNA in bacteria. RNA polymerase binds to promoter and initiates transcription.