High School Fruit Fly Lab Essay
Biology IB HL
March 25th 2010
Fruit Fly Lab
Genes can either be sex-linked or autosomal. If a gene appears mostly in one sex chances are the gene is sex-linked and if it appears frequently in both sexes it is most likely autosomal. Using Drosophila melanogaster, also known as the fruit fly, we will determine whether the gene is sex-linked or autosomal. Drosophila melanogasters have a relatively short life span and are an excellent organism for genetic studies because it has simple food requirements, occupies little space, is hardy, completes its life cycle in about 12 days at room temperature, produces large numbers of offspring, can be immobilized readily for examination and …show more content…
1. Obtain a vial of wild- type flies. Practice immobilizing and sexing these flies. Examine these flies and note the characteristics of their eyes, wings, bristles, and antennae.
2. To make handling easier, immobilize the flies with fly-nap, or by twirling the vial in ice for several minutes. Place the immobilized flies on a piece of filter paper inside a petri dish. Place this under a dissecting microscope to view the flies.
3. Distinguish male flies from female flies by looking for the following characteristics:
a). Males are usually smaller than females.
b). Males have dark, blunt abdomens, and females have lighter, pointed abdomens.
c). Only males have sex combs. which are groups of black bristles on the upper most joint of the forelegs.
4. Obtain a vial containing pairs of experimental flies. Record the cross number of the vial. This number will serve as a record as to which cross you obtained. These flies are the parental generation (P1) and have already mated. The female should have already laid eggs on the surface of the culture medium. The eggs represent the first filial, F1 generation and will be emerging from their pupal cases in about a week.
5. First week (today): Immobilize and remove the adult flies. Observe them carefully under the dissecting microscope. Separate the males from the females and look for the mutation(s). Note whether the mutation(s) is/are associated with the males or females. Identify the