10.4 Mutations identify the operator and the regulator gene Figure 10.9 fac gene synthesizes Mutations that defective re pressor that does not bind to dna inactivate the lacl gene cause the operon to be constitutively expressed 入 MV because the mutant repressor protein cannot bind to the Operon is transcribed and translated operator 消当Figure 10.9 Mutations that inactivate the lacI gene cause the operon to be constitutively expressed, because the mutant repressor protein cannot bind to the operator. 10.4 Mutations identify the operator and the regulator gene