the four principles of hereditary phenomena discovered and formulated by Gregor Mendel: 1) the law of independent unit characters, which states that characters, as height, color, etc., are inherited separately as units 2) the law of segregation, which states that body cells and primordial germ cells contain pairs of such unit characters and that when gametes are produced, each gamete receives only one member of each such pair 3) the law of dominance, which states that in every individual there is a pair of determining factors (see
gene) for each unit character, one from each parent; if these factors are different (
heterozygous), one character (the
dominant) appears in the organism, the other (the
recessive) being latent; the recessive character can appear in the organism only when the dominant is absent; hence in all crossbred generations, unit characters are shown in varying combinations, each appearing in a definite proportion of the total number of offspring 4) the law of independent assortment, which states that any one pair of characters is inherited independently, notwithstanding the simultaneous transmission of other traits: this principle has been modified by the discovery of linkage and pleiotropy
