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Introduction to Mendelian Genetics

Author(s): Lisa M. Meffert, PhD

Mendel’s Research on Particulate Inheritance

Mendel found that pea plants were easy to breed and had distinctive visual traits (phenotypes), such as plant height, pea color, flower color, and texture. First, he established pure-breeding lines for each of these traits (the P, or "parental" lines). When two of the same line were mated, the offspring always were identical to the parents. Next, he selected a particular characteristic, such as plant height, and then mated two parents that were pure bred for contrasting traits (tall and short). He found that all offspring looked liked one of the parental lines (in this case, all tall). He then crossed these offspring (the F1 or "first filial" generation). The resulting set of offspring (the F2 generation, or second filial generation) had a combination of ¾ of the phenotypes (tall) found in the previous generation (the F1). The remaining ¼ of the progeny looked like the other parental phenotype in the original cross (short).