fly lab - Jennifer O'Brien Bio 116 TA: Joe 11/10/06...

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Jennifer O’Brien Bio 116 TA: Joe 11/10/06 Mendelian Inheritance in Drosophila Melanogaster Introduction: The purpose of this several week lab was to learn hands on about the principles of Mendelian genetic inheritance by using the common fruit fly (Drosophila melanogaster) as our test subject. To understand the Mendelian modes of inheritance we crossed different phenotypes of flies and examined the outcomes to determine the mutant genotypes and their specific mode and pattern of inheritance. The modes of inheritance could be either autosomal or sex-linked and the patterns could either be dominant or recessive. The two theories of Mendelian inheritance are the principle of segregation; stating that each chromosome in a pair of homologous chromosomes separate during gamete formation, so that every gamete receives only one chromosome from the pair; and the principal of independent assortment, which states that each chromosomes in a pair of homologous chromosomes separates independently from the other chromosome so that the inheritance of one gene is not affected by the inheritance of another. In this specific experiment, we were provided with F0 generation flies (the parental generation) of two different mutants. After collecting virgin female flies, and crossing the two mutations twice to finally collect F2 generation flies, we were able to look at the phenotypic counts of each mutation in the F2 generation and
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produce a Chi-squared test to work backward to understand the mutation’s mode of inheritance. The common fruit fly (Drosophila melanogaster) was used in this experiment for several reasons. First of all, they are small and easy to contain and manage in a laboratory setting. Also, they have a short life style, able to reproduce in large quantities and not very complex in their genome. Lastly, the mutations in the fruit fly are easily recognizable. The life cycle of these small creatures is a short and simple one. They go through four stages (egg, larva, pupa and adult), all which lasts about two weeks. The pre-adulthood stages only lasts several days, and mating after adulthood can happen 8-12 hours after hatching from eclosion. We were given wild type flies, and flies with brown eyes and vestigial wing mutations (011), for our cross. The wild type flies have tan bodies and larger, well shaped wings.    While working through the procedure, we ran into problems with our 011 flies, and therefore were given another cross to complete as well which had wild types flies crossed with vestigial wings, and blue body mutations. From prior knowledge of Mendelian genetics, I hypothesize that the alleles would be passed on independently, and would show a 9:3:3:1,
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This note was uploaded on 04/07/2008 for the course BIOS 116 taught by Professor Kenna during the Fall '06 term at Lehigh University .

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fly lab - Jennifer O'Brien Bio 116 TA: Joe 11/10/06...

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