DNA+Cloning+and+Genotype+to+Phenotype

This exercise was designed to provide an exciting introduction to specific gene structure and function. In the experiment, students are given three plasmids (A -C) which are identified in the instructors guide. One plasmid (A) has a functional gene for the enzyme ß-galactosidase. The ß-galactosidase gene in the other plasmid (B) is inactive because it contains a segment of foreign DNA. Plasmid C contains the lux operon and bacteria that carry this plasmid glow in the dark. In the first part of the exercise, students analyze restriction digests of the plasmids in order to determine which plasmid should have a functional ß-galactosidase gene. In the second part of the exercise, the plasmids are introduced into E. coli by transformation and the color of the resulting colonies (blue or white) is then used to assess the functional status of the ß-galactosidase gene. The bacteria are also viewed in the dark for glowing in order to see which plasmid contains the lux operon.