Operon Updated +Created
Sequence of genes under a single promoter. For an example, see E. Coli K-12 MG1655 operon thrLABC.
A single operon may produce multiple different transcription units depending on certain conditions, see: operon vs transcription unit.
Transcription unit Updated +Created
A sequence of mRNA that can actually be transcribed.
Multiple different transcription units can be produced by a single operon, see: operon vs transcription unit.