[Gr. allēlōn, of one another]
Any of two or more different genes containing specific inheritable characteristics that occupy corresponding loci on paired chromosomes. A pair of alleles is usually indicated by a capital letter for the dominant and a lowercase letter for the recessive. An individual with a pair of identical alleles, either dominant or recessive, is said to be homozygous for this gene. The union of a dominant gene and its recessive allele produces a heterozygous individual for that characteristic. Some traits may have more than two alleles, but an individual has only two of them. For example, the genes for blood type, A, B, and O, are at the same position on the chromosome pair, but an individual has only two of these genes, which may be the same or different.
SYN: SEE: allelic gene; SEE: allelomorph
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