Choose the odd one out with respect to the transcription unit.
Transcription unit (TU) is defined as the segment of DNA between the sites of initiation and termination of transcription by RNA polymerase. More than one gene may reside in a transcription unit. The transcription unit consists of three regions i.e., promoter, terminator and structural gene.
Promoter: It is a region of the DNA to which the RNA polymerase binds and initiates transcription.
Terminator: It is a region of the DNA to which the RNA polymerase binds and stops transcription.
Structural gene: A structural gene is a segement of DNA that codes for any RNA or protein product other than a regulatory factor.
Operator gene: It is a segment of DNA that interacts with a specific repressor protein to regulate the expression of subsequent gene or gene set.