Dictionary > Hemizygous gene

Hemizygous gene

A gene in which it has no allelic counterpart or is present as only a single copy instead of the usual two copies in a diploid cell or organism.
For example, a gene wherein one of its pair is deleted is a hemizygous gene. In another example, most of the genes of the X chromosome and Y chromosome in human males are hemizygous since males have only one X chromosome (and one Y chromosome) (unlike females that has two X chromosomes).
Word origin: Greek hēmi- half + zygous > zygote.

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