Sunday, August 4, 2019
Genetic Observations Through The Studies Of Hybrid Corn, Single Gene Es
Genetic Observations Through The Studies of Hybrid Corn, Single Gene Human Traits, and Fruit Flies      The basic foundation of modern genetics was led by Gregor Mendel (Corcos, 1993). Mendel was not the first to experiment with heredity, and our Lyman Briggs biology class will not be the last to deal with genetics. Genetics is the science of heredity. In our lab, we had three main objectives. First, we evaluated our data on monohybrid and dihybrid corn cross seed counts against Mendel’s theoretical expectations of independent assortment and the segregation of alleles. Next, we used the Hardy-Weinberg Theorem to provide a theoretically expected value for allele frequencies for single human gene traits. Lastly, we dealt with Drosophila melanogaster and we examined red and white eye alleles to determine if this gene is sex-linked or autosomal.      During the mid 1800’s Mendel bred garden peas to study inheritance. He choose these plants because of their well defined characteristics and the ability to be grown and crossed (Campbell, 1996). Mendel wanted to know the genetic basis for variation among individuals and what accounted for the transmission of traits from generation to generation. Mendel followed traits for the P generation, F1 generation, and F2 generation. The P generation is the original true-breeding parents. Their hybrid offspring is the F1 generation, the first filial. The F2 generation is the second filial and is the self- pollination of the F1 hybrids. It was predominantly his research on the F2 generation that led to Mendel’s Law of Segregation and Law of Independent Assortment (Campbell, 1996).      Mendel’s Law of Segregation states that alleles sort into separate gametes. He formed this through performing monohybrid crosses. The F2 generation will have a 3:1 phenotypic ratio. By considering more than one trait Mendel formed his Law of Independent Assortment. He questioned whether traits were inherited independently or dependently. By performing dihybrid crosses he found that genes are independent and will form all possible combinations . Crossing two different traits resulted in a 9:3:3:1 phenotypic ratio (Campbell, 1996).      Thomas Hunt Morgan also had a major contribution in the study of inheritance. He was the first to associate a sp... ...ross, Mendel’s Law of Independent Assortment illustrated that four possible phenotypes form a 9:3:3:1 phenotypic ratio. For the single gene human traits experiment, we used the Hardy-Weinberg Theorem and equation to find the allele frequencies. For the experiment with Drosophila melanogaster we examined a fruit fly cross between red-eyed males and white-eyed females. We determined that this trait is sex-linked when the offspring were red-eyed females and white-eyed males. Throughout the genetics lab each purpose was determined and explained. A lot was learned about Mendel, genetics, and the hereditary process that makes us who we are today. Cited Literature Campbell, N.A. 1996. Biology. The Benjamin Cummings Publishing Co., New York, pp. 238-          279. Corcos, Alain F. and Floyd V. Monaghan. 1993. Gregor Mendel’s Experiments on Plant Hybrids.      Rutgers University Press, New Jersey, pp. 45-46, 76, 105-112, 133. Davis, M. 1996. Genetics. LBS 144 Laboratory Manual. The Lyman Briggs School, Michigan           State University, East Lansing, pp. 25-36.
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