Drosophila melanogaster, the fruit fly, has been used in genetics research for almost 100 years. In July the Year 13 biology students developed their "Drosophila Technique" by investigating a dihybrid cross which affects eye colour.
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In this investigation one gene produces a scarlet pigment in the eye, a gene on a different chromosome produces a brown pigment. The production of pigments is dominant. A fully homozygous scarlet-eyed fly was crossed with a fully homozygous brown-eyed fly. Members of the F2 generation are being counted here. |
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Note that the eyes are white, brown, scarlet and red. Year 12 Biology students: Refer to your dihybrid cross notes to explain how these four phenotypes have come about, work out their genotypes, and give the expected ratios. |
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The generation time for these flies is only ten days, so we can complete an experiment requiring two generations of flies in three weeks.
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