lac operon(redirected from Lac I)
Also found in: Encyclopedia.
a collection of adjacent bacterial genes responsible for the entry and metabolism of lactose; contains the genes coding for three enzymes and is flanked by a repressor and a promoter region to control expression.
lac operonA sequence of genes found in many bacteria that codes for the enzymes needed to break down lactose to glucose and galactose so that the sugars can be utilized. Studies on the lac operon have been important in genetic research. The lactose repressor protein controls the transcription of the lac operon.
lac operonthe genetic system of Escherichia coli that is required to metabolize lactose and on which the OPERON MODEL is based.
the lactose operon, a nucleotide sequence in Escherichia coli that controls the synthesis of the enzyme β-galactosidase comprising binding sequence motifs for the cap protein, which activates transcription, the repressor protein, which inhibits transcription, and a region with which RNA polymerase interacts. The first, best studied and best understood model for gene regulation.