Gene Regulation and the Lac Operon

Cells with the same DNA can look and function differently from each other; consider a photoreceptor cell and muscle cell. The difference between these two cells is the result of differential gene expression. Some genes are transcribed and translated in all cells at about the same level, but other genes may be expressed in one cell type but not another. This session will briefly outline some general principles of gene regulation. In addition, a specific example of gene regulation in bacteria will be presented in detail.

Learning Objectives

• To recall and understand the different mechanisms working together to regulate the Lac operon.
• To distinguish positive and negative regulatory mechanisms.
• To predict the phenotype caused by different mutations within the Lac operon.
• To justify the benefit to an organism of regulating genes.