-The regulator gene
codes for an active repressor protein.
-The repressor protein then binds to
the operator region of the operon.
-With the active repressor protein bound to
the operator region, RNA polymerase (the enzyme responsible for the
transcription of genes) is unable to bind to the promoter region of the
operon.
-If RNA polymerase does not bind to the promoter region, the three
enzyme genes (Z, Y, and A) are not transcribed into mRNA.
-Without the
transcription of the three enzyme genes, the three enzymes needed for the
utilization of the sugar lactose by the bacterium are not synthesized.
