| allele | <genetics> Any one of a series of two or more different genes that occupy the same position (locus) on a chromosome. Since autosomal chromosomes are paired, each autosomal locus is represented twice. If both chromosomes have the same allele, occupying the same locus, the condition is referred to as homozygous for this allele. If the alleles at the two loci are different, the individual or cell is referred to as heterozygous for both alleles. (15 Nov 1997) |
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| alleles | Mutually exclusive forms of the same gene, occupying the same locus on homologous chromosomes, and governing the same biochemical and developmental process. (12 Dec 1998) |
| allelic | Relating to an allele. Synonym: allelomorphic. (05 Mar 2000) |
| allelic exclusion | <cell biology, genetics> The process whereby one or more loci on one of the chromosome sets in a diploid cell is inactivated (or destroyed) so that the locus or loci is (are) not expressed in that cell or a clone founded by it. For example in mammals one of the X chromosome pairs of females is inactivated early in development (see Lyon hypothesis) so that individual cells express only one allelic form of the product of that locus. Since the choice of chromosome to be inactivated is random, different cells express one or other of the X chromosome products resulting in mosaicism. The process is also known to occur in immunoglobulin genes so that a clone expresses only one of the two possible allelic forms of immunoglobulin. (19 Dec 1998) |
| allelic gene | See: allele, dominance of traits. (05 Mar 2000) |
| allelism | The state held in common by alleles. Synonym: allelomorphism. (05 Mar 2000) |
| allelocatalysis | Self-stimulation of growth in a bacterial culture by addition of similar cells. Origin: G. Allelon, mutually, reciprocally, + catalytikos, able to dissolve (05 Mar 2000) |
| allelocatalytic | Mutually catalytic; denoting two substances each of which is decomposed in the presence of the other. (05 Mar 2000) |
| allelochemical | <cell biology> Substances effecting allelopathic reactions. See: allelopathy. (18 Nov 1997) |
| allelochemicals | Signal substances between individuals of different species. Compare: pheromones. Origin: G. Allelon, reciprocally, + chemical (05 Mar 2000) |
| allelomorph | Synonym: allele. Origin: G. Allelon, reciprocally, + morphe, shape (05 Mar 2000) |
| allelomorphic | Relating to an allele. Synonym: allelomorphic. (05 Mar 2000) |
| allelomorphism | The state held in common by alleles. Synonym: allelomorphism. (05 Mar 2000) |
| allelopathy | <cell biology> The deleterious interaction between two organisms or cell types that are allogeneic to each other (the term is often applied loosely to interactions between xenogeneic organisms). Allelopathy is seen between different species of plant, between various individual sponges and between sponges and gorgonians. (18 Nov 1997) |
| allelotaxis | Development of an organ from a number of embryonal structures or tissues. Origin: G. Allelon, reciprocally, + taxis, an arranging (05 Mar 2000) |