A: You want to create a genetic construct that will express the B-galactosidase enzyme encoded by E. coli's lacZ gene in Drosophila. In addition to the lacZ coding sequence, which DNA elements must you include in order to express this protein in flies if the construct could somehow become integrated into the Drosophila genome? Where should such DNA elements be located?B: In making your construct, you place inverted repeats found at the ends of a particular type of transposable element on either side of the lacZ coding region and all of the DNA elements required by the answer to part A. Since all the DNA sequences located between these inverted repeats can move from place to place in the Drosophila genome, it is possible to generate many different fly strains, each with the construct integrated at a different location in the genome. You treat animals from each strain with a chemical that turns blue in the presence of B-galactosidase. Animals from different strains show different patterns: some show blue staining in the head, others in the thorax, some show no blue color, etc. Explain the results and describe a potential use of your construct.

Views: 5,047 students