Fruit Fly Genetics

This worksheet includes two pages exploring traits in fruit flies. Fruit flies, scientifically known as Drosophila melanogaster, have earned their place as one of the most valuable organisms in genetic research. This tiny insect, measuring just a few millimeters in length, has contributed immensely to our understanding of genetics and developmental biology.

For genetic studies, students can grow fruit flies and explore how traits are passed through generations. For a basic level biology class, I focus on a few traits the follow Mendelian genetics inheritance pattern. This worksheet starts with a page on a single allele trait in the fly, the vestigial wing. Vestigial wings are recessive.

With beginning students, I find it helpful to give them a chart showing the genotypes and phenotypes. The one on the page is partially completed: GG = wings. Students complete the rest of the chart showing Gg = wings, and gg= vestigial wings.

Also, with beginning students, I don’t use the standard letter form (vg, vg+). Freshmen struggle with making Punnett squares and adding new symbols can make it even more difficult. I also avoid using letters that look the same as capitals or lowercase, like the letter V.

Sex Linkage in Fruit Flies

The second page explores sex-linked inheritance patterns. In fruit flies, there are many variants on eye color, with wild type flies having red coloration. Mutant flies can be sepia or white eyed. The white-eye trait is sex linked.

Page two follows a similar format. Students write down the letter combinations for each potential fly. This time, they must pay attention to the X and Y chromosome. The Y chromosome does not carry the gene for eye color, so males inherit their alleles from their mothers.

So, if a female with white eyes is crossed with a wildtype (red) male. All of the female offspring will have red eyes, and all of the male offspring will have white eyes. Surprising! If you really want to get crazy with fruit flies, you can order drosophila from biological supply companies.

If you wanted to explore more crosses with sex-linked genes, you can check out this worksheet that also includes calico cat inheritance and hemophilia, which is a human sex-linked disorder.