Termination of transcription

Confusingly the signal for termination of transcription is provided through a structure on the mRNA itself. After the last gene in the operon has been completely transcribed the RNA

                                            Figure:  Formation of the transcription complex.

polymerase continues transcription past  the  last gene’s termination codon. This part of the mRNA folds up into a stem-loop structure which causes the RNA polymerase to pause and cease transcription. The RNA polymerase then dissociates from the DNA and the mRNA it has generated leaving the complete transcript ready for the ribosomes to translate it into protein.

                                                            Figure:  RNA hairpin structure.