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noun, plural: heterozygotes

A nucleus, cell or organism possessing two different alleles for a particular gene


A cell or an individual may be classified based on zygosity (i.e. the degree of similarity or the dissimilarity of the DNA sequences in specific coding segments, or genes, on the homologous chromosomes). A cell or an organism may be homozygous, heterozygous, hemizygous, or nullizygous. The nucleus, cell or organism that is described as heterozygous means that the alleles on the matching loci of homologous chromosomes are not identical. Such nucleus, cell, or organism is also referred to as a heterozygote.

Humans and other diploid organisms have two sets of chromosomes (one set from the father and the other from the mother). Each maternal chromosome has a corresponding paternal chromosome to match with based on their loci. Each pair of chromosomes is referred to as homologous chromosomes. When the homologous chromosomes bear different alleles on the same loci, such organism is referred to as heterozygote. One of these alleles will manifest in the phenotype of the organism and the other will not. The allele that is expressed is said to be the dominant allele whereas the other one that is not is referred to as the recessive allele for a particular gene.

Word origin: Greek hetero ("different") + zygote


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Related form(s):

  • heterozygous (adjective, of, or pertaining to heterozygosity or a homozygote)