Around 1854, Mendel began to research the transmission of hereditary traits in plant hybrids. At the time of Mendel’s studies, it was a generally accepted fact that the hereditary traits of the offspring of any species were merely the diluted blending of whatever traits were present in the “parents.” For example the blending of a tall parent and a short parent would have an outcome of a medium child. In Mendel's findings, that theory was proved wrong, the offspring displayed a trait from one or the other parent. Mendel decided to practice his experiments on peas and flowers.
Mendel chose to study a small group of traits that occur in either of two forms, such as round versus wrinkled pea shape. He began by developing "pure-breeding" lines of each form. In a pure-breeding line, crossing two members gives only offspring that are identical to the parents for that trait. Mendel then crossed pure-breeding parents who had different forms of a trait. For example, he crossed a pea plant that produced only round peas with one that produced only wrinkled peas. All the offspring from this cross-developed only round peas; no wrinkled peas were found. When these offspring were crossed among themselves, however, both round and wrinkled were observed, in a numerical ratio of three round-pea plants for every one wrinkled-pea plant. Mendel explained these results by proposing that each visible trait is governed by the presence of two "factors," which may be the same or different in any individual. One of these factors is "dominant," while the other is "recessive."
In Mendel's experiments with the peas and flowers, he concluded with 7 traits:
Mendel chose to study a small group of traits that occur in either of two forms, such as round versus wrinkled pea shape. He began by developing "pure-breeding" lines of each form. In a pure-breeding line, crossing two members gives only offspring that are identical to the parents for that trait. Mendel then crossed pure-breeding parents who had different forms of a trait. For example, he crossed a pea plant that produced only round peas with one that produced only wrinkled peas. All the offspring from this cross-developed only round peas; no wrinkled peas were found. When these offspring were crossed among themselves, however, both round and wrinkled were observed, in a numerical ratio of three round-pea plants for every one wrinkled-pea plant. Mendel explained these results by proposing that each visible trait is governed by the presence of two "factors," which may be the same or different in any individual. One of these factors is "dominant," while the other is "recessive."
In Mendel's experiments with the peas and flowers, he concluded with 7 traits:
- flower color is purple or white
- flower position is axil or terminal
- stem length is long or short
- seed shape is round or wrinkled
- seed color is yellow or green
- pod shape is inflated or constricted
- pod color is yellow or green