Drosophila Melanogaster
Annie Wall
1/21/14
Biology II
Introduction
Mrs. Phillips instructed an experiment for the senior advanced biology class to conduct over drosophila melanogaster, or more commonly known as the fruit fly. The purpose of this experiment was to test the probability against the reality of the phenotype of the outcome in the F1 and F2 generations linking to the recessive and dominant traits. The hypothesis was that all the flies would come out to be winged in the F1 generation. Each senior was given many vials containing the initial parent generation. In the vials there were wingless or apterous which carries the ressive traits, and winged or wild which carries the dominate trait, flies. Each student collected virgins from each line of heredity and crossed them with the opposite trait in order to get the F1 generation and carry over with this into the F2 generation.
Materials and Methods
Once the flies were in the parent generation, all flies, minus the eggs and larvae, were removed and put into backup parent vials. Then the parent flies are removed. When larva appears on the sides of the vial then the parents are removed to be sure of no cross breeding. All the vials given to the students contain a fly medium mixed with an equal amount of water and four to five grains of yeast to support and feed the flies. The first step after removing the parents is to collect vials of twenty female virgins of each trait. Flies are removed within 12 hours of hatching to ensure they are virgins. To determine male from female flies, the flies were transferred to a different vial then put to sleep with flynap. Once asleep, each fly was examined under a microscope and separated by sex using a sorting brush. After two weeks without any visible larvae in the virgin vials, the flies are ready to be crossed. Virgin apterous flies are crossed with wild males, as well as virgin wild flies crossed with apterous males. When multiple vials of these types of crosses are made and are sufficiently reproducing, the virgin crosses can stop being made.
In approximately two weeks, pupae can be seen on the sides of the vial. At this time, the parents are removed. These new flies are classified as the F1 generation. At least 250 F1s from each lineage must be collected. These also must be removed and separated within twelve hours to ensure that they are virgins. From this point the flies no longer need to be sexed. The numbers and phenotypes of these are recorded and the flies are set to the side in vials of thirty to sixty, still separated by the original ancestry of wild or apterous.
Once the F1xF2 vials begin to have pupae and larva appears, the parents are removed and placed in backup vials. The flies that hatch from these F1 crosses are the F2 generation. These should be counted, recorded, and then put to sleep. When a total of 500 recorded F2 flies are reached, roughly 250 from each cross the experiment can now be concluded

Drosophila Melanogaster
Annie Wall
1/21/14
Biology II
Results and Discussion
The P1xP1 punnett square predicts the complete absence of apterous flies in the F1 generation, from both apterous by wild and wild by apterous crosses, a ratio of 4:0. This means that 100% of the flies have a winged phenotype. The actual results were 85% wild and 15% apterous. The F1xF1 punnet square cross predicts that 75% of the flies will be winged while 25% will show apterous. In the reality of the experiment the results were 83% showing the wild trait while 17% showed the recessive trait of apterous.

Drosophila Melanogaster
Annie Wall
1/21/14
Biology II
Conclusion
The experiment was conducted to test the probability against the reality of the outcome in the F1 and F2 generations. The hypothesis was that all the flies would come out to be winged in the F1 generation. This means that
100% of flies would show the winged trait. In reality the outcome of this experiment showed a 10% error. The cause of error could have been in the
P1xP1 cross. If the cross was not a true wild x apterous, the results would be skewed for both generations. It was hypothesized that in the F2 generation
75% would be will and 25% apterous. The actual results of the F2 generation were an 8% error. Due to the first error in the F1 generation this could be what caused the error in the F2.
Acknowledgements
I would first like to thank Mrs. Phillips for being such an amazing teacher and providing us the opportunity to do this experiment. Although you are our teacher we love you like you are family, you are an amazing person inside and out. This experiment was actually really fun. I must admit it was annoying and stressful at the same time. I would also like to thank my family for not killing me while I have to check flies at midnight after work banging my vials and getting mad when I would release flies. Also a big thank you to not only my classmates but my friends for keeping me calm when I really wanted to freak out. We all were stressed to our max with them, and possibly releasing about twenty flies every few minutes. I say anyone who thinks about taking the class should Mrs. Phillips is a great teacher!