Question

The polycistronic structural gene in lac operon is regulated by?

Answer 1

Lac operon:

1. Lac operon is composed of 3 structural genes (z, y, and a) which are normally involved in the metabolism of lactose.
2. There is one promoter, one operator, and also regulatory (i) genes.
3. The regulatory gene also produces a repressor protein that binds to the operator site. This blocks the transcription by the RNA polymerase.
4. When there is lactose, repressor protein binds to lactose & forms allolactose which cannot bind itself to the operator.
5. The RNA polymerase also binds to the promoter & polycistronic mRNA is produced.

The polycistronic structural gene in the lac operon is regulated by its regulatory genes and a promoter.