The Lac operon, proposed by Francois Jacob and Jacques Monod, is predominantly found in prokaryotes like E. coli, representing the first identified gene regulatory process in bacteria.
- Comprising an operator, promoter, three structural genes (lacZ, lacY, lacA), and a terminator, the operon governs the regulation of lactose, including its transport and metabolism.
- The structural genes (lacZ, lacY, lacA) encode beta-galactosidase, galactoside permease, and galactoside acetyltransferase, respectively.
- RNA polymerase binds to the promoter region (at the 3′ end of the template strand), initiating downstream movement for protein synthesis.
- Beta-galactosidase breaks down lactose into glucose and galactose, permease facilitates lactose entry into the cell, and acetyltransferase transfers acetyl groups from acetyl-CoA to beta-galactoside.
- The operon is active solely in the presence of lactose.