Regulation of Gene Expression
Often, the regulation of a gene is as important to the life of an organism as its presence. Numerous strategies for regulation of gene expression have evolved. These work to control synthesis of a gene's product and ultimately the phenotype produced by action of the gene product. The lac operon of E. coli is a paradigm for regulatory schemes and is an effective model for several basic concepts in the regulation of gene expression.
The genes for lactose metabolism in E. coli are arranged in an operon and confer upon E. coli the ability to regulate expression of genes for lactose metabolism. The lac operon is an inducible system that exhibits both positive and negative control.