Will the Recessive Allele of a Fruit Fly's Eye Color Be Exhibited in the Presence of a Dominant Allele?

Overview

Objectives/Goals The objective is to deteremine if a recessive allele will show in the phenotype of a Drosophila melanogaster eye color. Methods/Materials Sepia flies, which has recessive brown eyes, was crossbred with Wild flies, which had dominant red eyes. Their offspring#s eyes, looking exactly like the Wild, were compared to the parents by the process of paper chromatography. The chromatograms were only visible under a fluorescent black light. Results There was slightly less drosopterin (orange) pigment in the Heterozygous compared to the Wild. The xanthopterin (green-blue) pigment is very dark in the Sepia whereas very light in the Wild. The data was quantified by measuring the Rf value, pigment length, and using a spectrophotometer, which all measured the amount of pigment. There was a noticable difference between the Homozygous and Heterozygous eye pigment in the spectrophotometer at 4000 angstrom units, right at the lower edge of ultraviolet radiation. Sepia had the lowest Rf value, followed by the Heterozygous and Wild. The Heterozgyous almost had the exact same Rf value as Wild, but the Wild was slightly higher. Conclusions/Discussion The Wild#s eye color isn#t exactly the same as the Heterozygous#s, as shown in the Rf values, pigment lenghts, and spectrophotometer readings. This experiments proves that the dominant trait doesn#t override recessive trait completely, as stated in many textbooks.

Competition history

• CSEF 2002 Biochemistry/ Molecular Biology · Entry S0409

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