If 108 cells of a wild type strain are plated on agar plates containing phenyl-Gal, the rare colonies which grow are mainly spontaneous mutants affecting the repressor.
Se sementamos 108 células dunha cepa de tipo salvaxe nunha placa de ágar que contén fenil-Gal, as escasas colonias que crecen son principalmente mutantes espontáneos para o represor.