Pronounced ‘ah-lee-al’ and short for allelemorph (Greek word for ‘of another form’), it is a specific gene sequence that is one of a number of different mutated or natural forms of a particular gene or DNA sequence. A single allele for each locus on a chromosome is inherited from each parent. When the alleles of a pair are heterozygous (i.e., two different alleles of the same gene), one is dominant and the other is recessive. The dominant allele is expressed and the recessive allele is masked. Thus, a dominant allele is one that expresses its phenotypic effect even when heterozygous with a recessive allele. For example, if A is dominant over a, then AA and Aa have the same phenotype. A fixed allele is one in which all members of a population are homozygous (i.e., when both copies of the gene are identical), with the consequence that no other alleles for this locus can exist in the population.<\/p>\n
See Additive genetic effect<\/a>, Chromosome<\/a>, DNA (deoxyribonucleic acid, Epistatic\/epistasis<\/a>, Gene<\/a>, Haploinsufficiency<\/a>, Lactose tolerance<\/a>, Mendelian genetics<\/a>, Mutation (biology)<\/a>, Population genetics<\/a>, Prader-Willi syndrome<\/p>\n <\/body><\/html><\/p>\n","protected":false},"excerpt":{"rendered":" Pronounced ‘ah-lee-al’ and short for allelemorph (Greek word for ‘of another form’), it is a specific gene sequence that is one of a number of different mutated or natural forms of a particular gene or DNA sequence. A single allele for each locus on a chromosome is inherited from each parent. When the alleles of … <\/p>\n