BIO 100 Lecture Notes - Lecture 11: Zygosity, Allele, Gamete

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Mendel very carefully studied plant crosses and proposed a theory to explain heredity. Blending theory: certain characteristics of both (mixture) Created a mathematical model to explain crossing. Looked at peas, overtime existed in binary form. Seed shape, seed color, flower color, flower position, pod shape, pod color, and plant height. By crossing two true-breeding varieties of an organisms, scientists can study patterns of inheritance. Mendel crossed pea plants that varied in flower color. Shows a 3:1 ratio of purple to white flowers. The first concept is that alternative versions of factors account for variations in inherited characteristics. The alternative versions of these factors are now called alleles. The second concept is that for each character an organism inherits two factors one from each parent. The third concept is that if the two factors at a locus differ, then one (the dominant allele) determines the organism"s appearance, and the other (recessive allele) has no noticeable effect on appearance.