Exons - Coding segments. Leader segment - Precedes the sequuence coding for structural genes. Promoter - A sequence of DNA upstream from the transcription start site, leader sequence and structural genes. The promoter is not transcribed. Consensus sequence - does not vary very much from one organism to another.
Promoters have two consensus sequences.
35 bases upstream. Transcription start site - downstream from the promoter. Operator site - A site, on DNA, after the transcription start site where the repressor attaches which will modify transcription. It may be coding or non-coding. It is between leader and leader and start site for protein synthesis.