See Also:

lac(2) (iou)



lac noun2. [lak] M20.
[Abbreviation of LACTOSE.]
Biology. Used (usu. attrib. and printed in italics) orig. to denote the ability (of normal individuals) or inability (of mutants) of the bacterium Escherichia coli to metabolize lactose, and now also to designate (the parts of) the genetic system involved in this ability. Also, a lac+ bacterium; the lac operon.
Comb.: lac operon a group of adjacent genes in E. coli which, in the presence of lactose, cause the synthesis of the enzymes required for lactose metabolism.