University of South Carolina School of Medicine: Gene Mayer's "Genetic Regulatory Mechanisms"
Read this page and review the diagrams in the left panel. Click on Figures 1 to 10 for a graphical explanation of operon mediated bacterial gene expression.
Click http://web.archive.org/web/20160407040651/http://microbiologybook.org/mayer/geneticreg.htm link to open resource.