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Kaitlin Cough, Elizabeth Harnett

First Experiment: Monohybrid Cross

In this experiment we crossed a wild type male with a yellow bodied female. In the F1 generatio, we found that the ratio was 1:1, but the trait had switched: the females were all wild type, whereas the males were yellow bodied. We found this odd and thought, maybe it's sex linked? Then we looked at the F2 generation and found a 1:1:1:1 ratio. 25% females were wild types, 25% females were yellow bodied, 25% males wild type, 25% males yellow bodied. We then determined that yellow bodies was indeed a sex linked trait and that it was recessive.

F1:

X^YB X^YB

X⁺ X^YBX⁺ X^YBX⁺

Y X^YBY X^YBY

F2:

X⁺ X^YB

X^YB X^YBX⁺ X^YBX^YB

Y X⁺Y X^YBY

In our next experiment we wanted to try a dihybrid cross, however caused us a lotof trouble. We wanted to cross a wild type female with a curly winged and aristepedia antenae male fly. However, when we crossed them we found that our F1 generation had a 1:1:1:1:1:1:1:1 ratio which seemed rather odd. We decided to focus on the aristepedia atenae trait first.

We then then did a cross between a female heterozygote and a male heterozygote (for the aristepedia antenae trait) , this was our Punnet Square:

AR +

Ar ARAR Ar+

+ Ar+ ++

We had found before that the ratio was only 2:1, when it should have been 3:1 (like the Punnet square above). We determined that the AR homozygous dominant trait was lethal and that is why the ratio changed.