Allele

One of the different forms of a gene that can exist at a single locus (spot on a chromosome). Also one of the different forms of any segment of a chromosome.

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Any one of a series of two or more different genes that may occupy the same locus on a specific chromosome. As autosomal chromosomes are paired, each autosomal gene is represented twice in normal somatic cells. If the same a. occupies both units of the locus, the individual or cell is homozygous for this a.. If the alleles are different, the individual or cell is heterozygous for both alleles. See DNA markers. SEE ALSO: dominance of traits. SYN: allelomorph. [G. allelon, reciprocally]

- codominant a. codominant.

- silent a. SYN: amorph.

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al·lele ə-'lē(ə)l n

1) any of the alternative forms of a gene that may occur at a given locus

2) either of a pair of alternative Mendelian characters (as ability versus inability to taste the chemical phenylthiocarbamide)

al·le·lic -'lē-lik, -'lel-ik adj

al·lel·ism -'lē(ə)l-.iz-əm, -'lel-.iz- n

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(allelomorph)

n.

one of two or more alternative forms of a gene, only one of which can be present in a chromosome. Two alleles of a particular gene occupy the same relative positions on a pair of homologous chromosomes. If the two alleles are the same, the individual is homozygous for the gene; if they are different he is heterozygous. See also dominant, recessive.

• allelic adj.

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al·lele (ə-lēlґ) [Gr. allēlōn of one another, from allos other] one of the two or more alternative forms of a gene that can occur at a particular chromosomal locus and that determine alternative characters in inheritance. In diploid species, there are two alleles, identical or differing, for each specific locus of an autosomal chromosome, one on each chromosome of a homologous pair. allelic adj