What are the advantages of the operon organization within the bacterial chromosome?

A major advantage is that it leads to the synthesis of groups of functionally related enzymes, usually from a single mRNA transcript. Since a functional pathway must be activated in terms of all of its components, the operon affords an all-or-none response that serves efficiency. The control mechanisms existing for turning on or turning off the operon make the operon sensitive to those changes in the environment to which the bacterial cell must adjust.

The ability of the cell to fashion repressors that are functional as well as repressors that are nonfunctional permits a broad variety of environmental triggers to exert their effects. Inducible systems may be activated by agents that tie up the repressor, and constitutive systems may be shut off by corepressors that activate initially ‘‘blank’’ repressors. Further fine tuning is achieved by the participation of CAP protein and cyclic AMP in the activation of the promoter site.