BIOL 1020 Lecture Notes - Lecture 23: Mendelian Inheritance, Sister Chromatids, Genetic Variation
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Origins of genetic variation among offspring: the behaviour of chromosomes during meiosis and fertilization is responsible for most of the variation that arises in each generation sexual reproduction create a tremendous amount of variation. Three key mechanisms contribute to genetic variation: independent assortment of chromosomes crossing over random fertilization. Independent assortment of chromosomes: homologous pairs of chromosomes orient randomly at metaphase i of meiosis. In independent assortment, each pair of chromosomes sorts maternal and paternal homologous into daughter cells independently of the other pairs. 1. distinguish between the following terms: somatic cell and gamete, autosome and sex chromosomes, haploid and diploid describe the events that characterize each phase of meiosis. 2: name and explain the three events that contribute to genetic variation in sexually reproducing organisms. Mendel used the scientific approach to identify two laws of inheritance: mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments.