One of two alternative forms of a genes that can have the same place on homologous chromosomes and are responsible for alternative traits; SYN. allelomorph.
One of two or more alternative forms of a gene at a given position (locus) on a chromosome, caused by a difference in the DNA. Blue and brown eyes in humans are determined by different alleles of the gene for eye color.
Organisms with two sets of chromosomes (diploids) will have two copies of each gene. If the two alleles are identical the individual is said to be homozygous at that locus; if different, the individual is heterozygous at that locus. Some alleles show dominance over others.

Biology, one of a pair of alternative contrasting inheritable characteristics; gene carrying that characteristic.

Of or relating to alleles; SYN. allelomorphic.

Presence of genes that cause hereditary changes (Genetic)