Allele

allele An allele is one of two or more alternative forms of a gene that can exist at a single locus. Each allele therefore has a unique nucleotide sequence and may lead to different phenotypes for a given trait. If the alleles for a gene are identical, the organism is called homozygous. But if the alleles are different, the organism is heterozygous.

And If two alleles are different, one becomes dominant and is fully expressed in appearance in the organism. While the other is recessive and has no noticeable effect on the appearance of the organism.

Allele is shown in the color of your eyes, determined by the genes inherited from your parents. The gene for brown eyes is dominant and overrides genes for other eye colors. The gene for blue eyes is recessive and will appear when there are no genes for other eye colors. A person with brown eyes may have a recessive, or “hid­den,” gene for blue eyes. Therefore, two brown-eyed parents may each give a recessive gene for blue eyes to their child, who would then have blue eyes. Gray, green, and other eye colors result from a complex mix­ing of different eye color genes.