What is an operon? Describe the major steps involved in an operon?
An operon is a group of controllers & structural genes which control the catabolism of the cell genetically lactose operon/lac operon. When inducer or lactose is absent:- The lac regulator gene synthesizes a repressor protein by transcription & translation. This repressor protein binds with the operator site of lac operon & blocks RNA polymerase. Thus, RNA polymerase is unable to transcribe mRNA & structural genes are unable to translate enzyme B- galactosidase. When inducer or lactose is present: The lac regulator gene transcribes mRNA & synthesizes active lac repressor protein & at the same time lactose is converted into isomer allolactose. Allolactose binds to an active lac repressor due to which it is converted to an inactive repressor. This inactive repressor is released from the operator site of lac operon & RNA polymerase binds to promoter & starts to transcribe mRNA & forms β-galactosidase which converts lactose into glucose vs galactose. Thus, the presence of lactose determines whether or not lac. The repressor is bound to the operator & genes are expressed on not
