https://doi.org/10.1351/goldbook.O04301
A functional unit consisting of a promoter, an operator and a number of structural @G02604@, found mainly in prokaryotes. The structural genes commonly code for several functionally related @E02159@, and although they are transcribed as one (polycistronic) @M03857@ each is independently translated. In the typical operon, the operator region acts as a controlling element in switching on or off the synthesis of mRNA.