Alleelide

Alleelide, the Estonian plural form of allele, are alternative forms of a gene that occupy the same locus on homologous chromosomes. An individual typically carries two alleelide for most genes, one inherited from each parent. The specific pair, along with interactions with other genes, helps determine traits. Alleelide arise through mutation and are maintained in populations by inheritance and natural selection.

Alleelide can be identical (homozygous) or different (heterozygous). In many cases, one allele is dominant over another, masking the effect of the other in the phenotype; in other cases, alleelide are codominant or show incomplete dominance. The combination of alleelide in the genotype influences the observable characteristic, or phenotype, of an organism.

At the population level, many loci exhibit polymorphism, where multiple alleelide variants are common. Allele frequencies change due to mutation, natural selection, genetic drift, and gene flow. Studying alleelide distributions helps researchers understand evolution, disease risk, and variation in traits across individuals and populations.

Examples and applications include blood type determination, where different alleelide influence phenotype, and mutations such as the HbS allele in sickle-cell disease. In research and medicine, alleelide are central to genetic testing, genome-wide association studies, and personalized medicine. In agriculture and animal breeding, selecting specific alleelide combinations assists in achieving desirable traits.