Many inherited characteristics are controlled by the interaction of two genes, one from each parent. During meiosis, parent cells divide and contribute half their chromosome complement to the egg or sperm. After fertilization, the zygote contains a pair of each chromosome; each pair has genes for the same traits at corresponding locations. Alternate forms of the gene for a specific trait are called alleles, which may be dominant or recessive. See: allele; chromosome; gamete; gene; meiosis
Mendel's law of segregation states that as the gametes are formed, the gene pairs separate and do not influence each other.
Mendel's law of dominance resulted from his observation that crossing a tall strain of peas with a short strain resulted in the expression of the dominant trait, in this case tallness. Thus, a dominant trait will appear in the individual even if only one allele for it is present in the genome.
Mendel's law of independent assortment states that traits controlled by different gene pairs (such as height and color) pass to the offspring independently of each other.