20 Operon laktozowy, kontrola transkrypcji

polymerase    _{toc mRNA}

Inducer-repressor complex does not bind to operator

Figurę 5-25

(a) In the abseńce oi an induccr such as allolactosc. thc lac reprcssor binds to the operator (O), thereby preventing RN A polymerase from transcribing the Z, Y, and A gcnes of the lac operon. (b) On binding inducer. the lac reprcssor dissociates from the operator, which permits RNA polymerase to bind to the promotor (P) and transcribc the Z. Y. and A gencs. fi Se© Guided Exploration 2: Regulation of gene expression by the lac repres-sor system