Fruit Fly, Drosophila melanogaster, genetic cross - Research Paper Example

This basic level of research upholds the future of genetic research and leads into exciting new discoveries for the future. Introduction: The insect species known as Drosophila melanogaster, or the fruit fly, is an extremely valuable model for genetic research. Both current and historical discoveries have been made using fruit flies. Research on gene function all the way up to the Nobel Prize-winning level has been performed using these insects (Mummery, Wilmut, Stolpe, & Roelen, 2010). One famous example of historical research is that of Thomas Hunt Morgan of Columbia University in the early 20th century.

Morgan had been hoping to study spontaneous mutation, but instead found something far more useful: he was the first to understand sex-linkage in hereditary traits (Kandel, 2000). Fruit flies are so valuable as research models in part because of the peculiarity of animal evolution that resulted in the genetic structure of the fruit fly being similar to much more complex animals such as humans (Mummery et al., 2010). Because of this, developmental and cellular growth activities are very similar, and results learned from Drosophila melanogaster can be extrapolated into research potential for other organisms.

Their rapid generation time and small size mean that while other organisms could be extrapolated in the same way, fruit flies are ideal for laboratory work in a way that rodents or larger mammals are not. They are also commonly used because the sequencing of their genome is functionally complete, making research into gene function more efficient. Once a gene sequence is known, it is easier to follow that gene through breeding and determine its function (Celniker et al., 2000). The most basic level of fruit fly genetic studies involves crossing and observing the results of visible phenotypic mutations.

The most obvious of these phenotypic mutations involve the wings, as these are easily seen under low levels of magnification. Of these obvious wing mutations, the most easily identified is the apterous phenotype. Flies possessing the apterous phenotype completely lack wings and are flightless. Examples of the various wing mutations can be seen in Figure 1 below. Fig. 1 Drosophila melanogaster wing mutations. 1 = notch, 2 = delta, 3 = vestigial, 4 = antlered, 5 = curled, and 6 = apterous (Shevchenko, 1968) Since this mutation is so easily identified, it reduces the chance of observational error when counting the results, and so the apterous mutation is the one being studied in this experiment.

The apterous phenotype is recessive, and a cross between these apterous flies and the wild-type is a simple monohybrid cross. Therefore, using Mendel's laws as a guide, the F2 generation of this cross is hypothesized to produce a ratio of wild-type to apterous flies of 3:1 (Flagg, 1981). This is the null hypothesis. Conversely, the alternate hypothesis is that the ratio will be something other than 3:1. Materials and Methods: The materials used in this experiment were pure-bred wild-type Drosophila melanogaster, pure-bred apterous Drosophila melanogaster, plastic culture vials and stoppers, food media made from Formula 4-24 Instant Drosophila Medium, used for fly growth, breeding, and storage.

For the counting and observation portions of the experiment, the materials needed were an ice water bath, petri