Fruit Flys Essay
From simple heredity experiments with garden peas, to cloning sheep, the field of genetics has come a long way. Now we are closer to mapping out the human genetic map due to advances in technology, and years and years of research. Perhaps the most influential and groundbreaking scientist, Gregor Mendel, he was responsible to provide a path to where genetics is now today with his experiments of garden peas. In lab, fruit flies were crossed to observe inheritance patterns in their offspring. The motivation for this was to further understand how genes and characteristics are inherited.
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To use fruit flies would be much more effective and easier because of a couple of reasons. The genetic makeups of the flies only consist of 4 pairs of chromosomes. This makes it easier to spot characteristics, and is easily distinguishable. Another plus to using flies is that fruit flies can produce a whole new generation of offspring in two weeks, which is very convenient for researchers. This is why files are used instead of humans, but not only time, ethics have also been a major, if not the most important factor.
The traits observed here in this experiment were the wing types, whether vestigial or normal, and the eye color, whether brown or white. The genotype of the vestigial wing was a homozygous recessive vv. The normal wings were either Vv, or VV. The eye color was denoted by the genotype BB, and Bb for brown, and bb for white. The first generation Lines A and B were observed and then crossed to form the F1 generation. The F1s were then observed and then crossed to form the F2 generation. Genetic Hypothesis
The F1 generation hypothesis is that with the Line A, B cross, the F1 for our group will be expected to be heterozygous dominant (VvBb) at both loci. This is because of the cross of Line A, which was consisting of Males with the genotype of vvBB, and of line B that were females with the genotype VVbb. As far as the F2 generations go, the phenotypes are expected to have a 9:3:3:1 ratio. There should be 9 brown, normal fruit flies, and 3 of each the brown, vestigial fly and the white, long fly. Finally, there is expected to be only one white, vestigial fly that possesses homozygous recessive alleles in both loci.
There is a chance that there may be different outcomes to the F2 generation due to the possibility that the Line A and the Line B generation were not all homozygous dominant in wing type for females and eye color in males. Such a genotype in the males, vvBb, and such in females, Vvbb, may lead to a different ratio in the F2 offspring. Methods In the lab section, we observed two vials containing the Line A and B species. In order for us to further examine the flies, we knocked out the flies with a chemical anesthetic known as Fly Nap. Placing the wand covered in Fly Nap into the vial, we knocked out the flies.
We then spilled the flies onto a piece of paper and examined them under a light microscope. What were examined were the physical characteristics, i. e wing shape, body shape, eye color, body color, foreleg comb, and eye color. This was done to both the Line A and Line B flies. The Line A, B offspring, F1, were then observed under the same circumstances, and this time only the eye color and wing type were focused upon. The F1 were then left for 2 weeks to produce F2 offspring. The F2 was once again observed in the same manner as the F1 generation. Data was gathered, and calculations were made.