The Genetics of Beta-galactosidase— Encoded by the lacZ gene in E. coli— Laboratory Exercises to Illustrate Gene Regulation

 

Susan J. Karcher, Kristene L. Henne, & Deborah A. Anderson

Tested Studies in Laboratory Teaching, 2008, Volume 29

Abstract

Mutations of E. coli studied by Jacob and Monod led them to develop a model of transcriptional regulation of the lac operon by the lac repressor for which they received a Nobel Prize in 1965. This exercise uses E.coli strains with mutations in the lac operon to demonstrate the regulation of beta-galactosidase production. This exercise is used in a sophomore biology majors genetics and molecular biology laboratory at Purdue University. Students identify the nature of the mutations in each strain based on their determination of the beta-galactosidase activity of each strain. This laboratory enhances the students’ understanding of gene regulation.

Keywords:  beta galactosidase, Lac operon, lactose-operon inducer, gene regulation, lac repressor

University of Kentucky (2007)