Drosophila Melanogaster Lab Report

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Introduction: Gregor Mendel discovered the basic principle of heredity through studying one single constant trait. Mendel began his experiments in his garden at the monastery with pea plants; he recognized two main principles (biography.com). These two principles later became known as Principle of Mendelian Genetics, which is broken into two laws: the Law of Segregation and Law of Independent Assortments. Law of Equal Segregation: The Law of Segregation is Mendel’s first law. This law states that a pair of traits separates so that each gamete receives only one copy of the trait. As research continued, Oscar Hartwig proposed the idea of meiosis (Wood, 2009), during which a sperm and egg each give half of their genetic material (traits) to their offspring. Each gamete after meiosis has half of their genetic make up from paternal and maternal gametes. Law of Independent Assortment: The Law of Independent Assortment states that different gene pairs assort independently in gamete formation (Griffiths, Wessler, Lewontin & Carroll, 2008). When Mendel only experimented with one trait (monohybrid cross), the result was always a 3:1 ratio between the dominant and recessive trait. Mendel experimented with two traits (dihybrid cross) and observed a 9:3:3:1 ratio. From this result, Mendel concluded that the traits were independent of one another (Griffiths, Wessler, Lewontin & Carroll, 2008). We now know this ratio of 9:3:3:1 shows that the two genes are unlinked. In the 1900’s, Drosophila melanogaster, commonly known as the fruit fly’s became a choice model organism for genetic research. Fruit flies were a choice model because they are small, easy to raise, have short life cycles, and females give rise to hundreds of fertilized eggs. Thomas Morgan studied Drosophila melanogaster during the 1900’s and discovered sex linkage and genetic recombination

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