Fruit Fly Lab Report

Kaitlin Fair

Dr. Andrew

Genetics- Bio 222

Drosophilia Melanogaster and their sex-linked trait: eye color

Introduction(1-2 pages): Drosophila Melangoaster, fruit flies, are a model organism for sex linked traits such as eye color. This species reproduces efficiently. Males can mate with multiple females throughout their life, while a female fly stores the sperm she receives forever. Because a female fly is only able to reproduce once in her lifetime, when experimenting with flies it is typical to put a larger amount of females in a vial than males. This species is sexually dimorphic so there are phenotypic signs that allow us to distinguish between the biological sexes of the organisms. However, while the flies are still young they are light

It determines how similar the predicted results were to the real results. This number can be used to tell how accurate our results were. Figure 1 and figure 2 both have 2 degrees of freedom because they only have three different phenotypic outcomes from the cross. Although there was only three intended phenotypes, orange-eyed flies were produced. These flies were not produced by an error in breeding, they were rather the result of a defect in the gene that produces red pigments. The defect involves their white gene not fully making all of the red pigment that it normally does. (WEBSITE

This X2 value is even larger than the 9.210 value that leads to a P value of 0.01. This means that figure 1’s data leads to a rejection of the hypothesis because the data does not support T. H. Morgan’s work. Similarly, the class data with red and orange male flies combined from the F2 cross had a X2 value of 65. This value is much higher than the highest X2 value provided, 9.210. Again the hypothesis would be rejected because the data does not support T. H. Morgan’s work. The X2 analysis for figure 3 leads us to accept the hypothesis because it supports T. H. Morgan’s work. This conclusion is drawn from my individual vial flies because I had a different cross, which lead to four different phenotypes and three degrees of freedom. The X2 value of my data is 1.9032, which is within a P value of 0.70 and 0.50. A P value above 0.05 leads the hypothesis being accepted. Although my data resulted in supporting the hypothesis, I think my numbers could have been better. During week 5 as I transferred my flies to a single vial, a moderate amount of flies escaped. In the future, it would be beneficial to do a few trial transfers to make sure that you have the technique down prior to actually transferring