Operon Hypothesis

Describe the operon hypothesis and how it explains the control of the messenger RNA production and the regulation of protein synthesis in bacterial cells.

The operon is a group of genes coding for proteins with related functions and they are arranged in units. The operon is made up of the promoter, structural genes and the operator. Transcription depends on the regulator, it may be located anywhere on the bacterial chromosome. The regulator codes for the repressor, which binds to the operator. When the repressor is bound to the operator, it blocks the promoter. Therefore the RNA polymerase either can't bind to the DNA molecule or it can't begin its movement along the molecule. No transcription can occur. The repressor depends on the effector, which allows it to bind to the molecule. It can either activate or inactivate the repressor.

The lac operon in bacterial cells gave the first clue that such a gene occurred in