Fruit Fly Phenotypes

Genetics is all around us. One may observe heredity in many different forms. For example, Laboratory Three: Dihybrid crosses using Drosophila melanogaster, was assigned to observe Fruit Fly phenotypes. Around the 1920s, Thomas Hunt Morgan experimented with this same species to detect mutations and discovered X-linkage, various recessive and dominant phenotypes, and also that genes are located on chromosomes (Klug, et al. 2013). In the experiment that took place over the course of a few weeks, four different phenotypes were viewed. The predictions that were made before analyzing any data concluded that since the parental cross showed little mutation, the F1 cross (the next generation), would show little evidence of mutation as well. The

A plastic vial for the parental cross was used to first breed them to get the outcome, the F1 cross. Making the vial was a very important step in crossing the Drosophila because for the next few weeks while experimenting, this would be the environment in which they would inhabit. The vial consisted of Formula 4-24 Blue Fly Medium, ddH20 (not too much), and yeast. After getting the right mixture of those materials settled, a plastic netting for culture was added to make the habitat more “fly friendly.” Lab partners labeled the vials with colored tape that their initials were written on with a Sharpie. The vials were then stopped with a foam stopper to prevent the flies from escaping while a cap was attached at the top. When it came time to count and observe the phenotypes, the flies were shimmied into another container where they were put to sleep using Fly-Nap a type of Drosophila anesthetizer. After knocking the flies out, partners usually used a note card to dump their flies on. A dissecting microscope was used without the light because the light would kill the flies. So instead, a lamp with a fluorescent bulb was used to shine light. Often paint brushes were used to maneuver the flies in the sight of the scope. After detecting and recording all phenotypes, flies were dropped into a fly-morgue where they would die. This step was taken to prevent the flies from getting mixed with the hatching