Essay on A Study Of Inheritable Traits In Fruit Flies

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A Study Of Inheritable Traits in Fruit Flies

INTRODUCTION

The Drosophila melanogaster, more commonly known as the fruit fly, is a popular species used in genetic experiments. In fact, Thomas Hunt Morgan began using Drosophila in the early 1900’s to study genes and their relation to certain chromosomes(Biology 263). Scientists have located over 500 genes on the four chromosomes in the fly. There are many advantages in using Drosophila for these types of studies. Drosophila melanogaster can lay hundreds of eggs after just one mating, and have a generation time of two weeks at 21°C(Genetics:
Drosophila Crosses 9). Another reason for using fruit flies is that they mature rather quickly and don’t require very much space.
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Next, we removed the F1 generation flies to prevent breeding between the two generations. Acting as Dr. Kevorkian, we gave the F1 generation a lethal dose of the seemingly harmless anesthesia, fly-nap. A trumpet solo of "Taps" played in our minds as we said goodbye and placed them in the fly morgue. We allowed the F2 larval generation to incubate for two weeks. The experiment called for one week of incubation, but Easter fell during that week which interfered with our lab time.
After the two weeks, the F2 flies were also terminally anaesthetized. Only, before saying goodbye, we separated the flies according to sex and eye color(wild-type,red or mutant, sepia), recording the results in Table 1. The same method was used it the dihybrid cross, except, instead of one trait, two traits were observed. The traits were eye-color(wild-type, red or mutant, sepia) and wing formation(wild-type, full or mutant, vestigial). The F1 generation for the dihybrid cross came from a cross between a male homozygous wild-type for eyes and wings, and a female homozygous for sepia eyes and vestigial wings. The results of this cross were recorded and appear in Table 2.

RESULTS

The monohybrid cross of Drosophila melanogaster produced 25,893 flies for all of the sections combined. Of those flies, 75.9% had wild-type(red) eyes, and 24.1% had mutant(sepia eyes). Overall, more females were produced than males.

TABLE 1: F1 Generation Monohybrid Cross of Drosophila
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