Drosophila melanogaster were mated in labs 8, 11, and 13 to illustrate how the sex-linked genes are passed on from one generation to the next. This was accomplished by crossing different genotypes. In order to do this, the flies first had to be put to sleep, then counted under a dissecting scope and finally separated in to groups of red-eyed females, white-eyed females, red-eyed males, and white-eyed males. For the F1 a generation my results were 22 red-eyed males, 0 white-eyed males, 47 red-eyed females, and 0 white-eyed females. The expected ratio was 1:0:1:0, which was not far off from 1:0:1.2:0. The F1 b results are as follows: 0 red-eyed males, 20 white-eyed males, 37 red-eyed females, and 0 white-eyed females. The expected ratio was 0:1:1:0. The actual ratio was 0:1:1.7:0, this was a little farther off but I still accepted it. The results of the F2 a cross were 16 red-eyed males, 20 white-eyed males, 44 red-eyed females, and 0 white-eyed females. The excepted ratio was 1:1:2:0 which was exactly the same as the actual ratio, therefore I accepted it. Finally the F2 b cross results were 22 red-eyed males, 20 white-eyed males, 23 red-eyed females, and 15 white-eyed females. The expected ratio was 1:1:1:1 which is the same as actual ratio, thus I accepted it. Each time any part of this experiment was conducted all of the data was observed and recorded. The parental cross yielded the F1 generation and the F1 cross yielded the F2 genotypes and genotypes for both a and b, this was the goal of the over all experiment. All of the expected ratios and the actual ratios in this experiment were accurate.
The purpose of labs 8, 11, and 13 is to gexamine the genetic effects of sex-linkageh (Oaks, Engel, & Nelson). Genotypes and phenotypes were determined for the F1 and F2 generations (for each generation there were both an A and a B). The ultimate goal of these labs was to find the genotype and phenotype of the F2 generation.
Drosophila is used in this experiment to demonstrate genetics and evolution because they are easy to come by and have a short life span. gIt has only four chromosomes pairs: 3 pairs of autosomes and one pairs of sex chromosomes (XX female, XY male)h (Oaks, Engel, & Nelson 2002). Fruit flies lay their eggs in cracked produce where they hatch about twenty-four hours later. The eggs are .5 mm long and ghave two slender filaments near the head endh (North Carolina State University 2000). The cream colored maggots then eat the fruit in which they were hatched in until they are full grown, 5 mm long. This usually takes four days. Next the larva forms a yellowish-white pupa that is approximately 3 mm long. The pupa then turns into brown four days later and an adult fly emerges. The adult flyfs yellowish body is 3 mm long with dark bands. The female fly is ready to lay her eggs within two days. She lays about 500 eggs in all. For best...