Difference between revisions of "Zygosity"
(Created page with "Zygosity is a way of classifying genotypes. Simply put, if the two copies of a gene in a diploid organism are the same alleles, e.g. ''w''<sup>+</sup>/''w''<sup>+</sup>, the...") |
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Less commonly we can talk about hemizygotes where an organism only has one copy of a gene. For example most genes on an X-chromosome are present as only one copy in males. Individuals can also be hemizygous because of an insertion or deletion. | Less commonly we can talk about hemizygotes where an organism only has one copy of a gene. For example most genes on an X-chromosome are present as only one copy in males. Individuals can also be hemizygous because of an insertion or deletion. | ||
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| + | A fourth term, nullizygous, seems to have an inconsistent definition. It is sometimes used to refer to cases where both copies of the gene are completely missing, as in a homozygous deletion. However, it sometimes is used to refer to being homozygous for inactive null alleles (amorphs). | ||
Latest revision as of 02:35, 15 July 2014
Zygosity is a way of classifying genotypes. Simply put, if the two copies of a gene in a diploid organism are the same alleles, e.g. w+/w+, the individual is a homozygote. If the two alleles are different, e.g. w+/w-, the individual is a heterozygote.
Less commonly we can talk about hemizygotes where an organism only has one copy of a gene. For example most genes on an X-chromosome are present as only one copy in males. Individuals can also be hemizygous because of an insertion or deletion.
A fourth term, nullizygous, seems to have an inconsistent definition. It is sometimes used to refer to cases where both copies of the gene are completely missing, as in a homozygous deletion. However, it sometimes is used to refer to being homozygous for inactive null alleles (amorphs).
