Fruit FLy Lab
...s. We prepared 2 platic vials fort he new culture. We put 5mL of instant potato meal containing vitamins and minerals in each vial. We then added 11mL of water and 2-3 grains of yeast. We anesthetized the flies using .5” of water and an alka-seltzer tablet to produce carbon dioxide. Once the carbon dioxide hit the fruit flies, we put them onto the cold surface of a frozen broccoli box. This prolonged the anesthetic long enough for sex determining observations. Looking at the flies on the surface of the box under a micropscope, we determined the sex of the flies. Males fruit flies were characterized by the external genitalia or a darker color than the female, bristles on the posterior of the abdomen, and “sex combs” on the first pair of legs. Female fruit flies were characterized by a lighter color and the appearance of anal plates covering the ventral surface. Once sex was determined, 4 males and 4 females were put into the vial containing the food, and were stored on a shelf to await reproduction. Week 2: After allowing 2 weeks for the P1 generation to breed successfully, we were able to closely examine the first filial generation (F1). Traces of the F2 generation were already visible, (eggs and larvae), but were disregarded until they could be accurately analyzed. We anesthetized the flies using the water and alka-seltzer and examined them to find almost all wild type phenotypes. The sexes and phenotypes of the F1 generation are as follows: Wild Type Sepia/Wild Vestigial/Wild Vestigial/Sepia Total Female 65 1 7 0 73 Male 39 0 5 0 44 Total 104 1 12 0 117 Our null hypothesis would be that there would be equal numbers of males and females in the F1 generation. We then calculated a chi-square value of 7.18 which exceeds the chi-square value of 3.841 from the table. Because of this we were forced to discard our null hypothesis. Week3: Once our second filial generation (F2) had matured, we anesthetized them using the same alka-seltzer procedure once again. We then examined them on the box of broccoli under the microscope to determine their sexes and phenotypes. The sexes and phenotypes of the F2 generation are as follows: Wild Type Sepia/Wild Vestigial/Wild Sepia/Vestigial Total Female 31 10 13 4 58 Male 29 6 11 3 49 Total 60 16 24 7 107 Examinations of the F2 generation showed the presence of the two mutations in the phenotypes of the flies. In order to produce these phenotypes, the genotypes for these flies are as follows: E e EE Ee Ee ee Let E stand for wild type/dominant eye color. E Let e stand for sepia eyes, the recessive mutation. e ...