Zygosity

Zygosity a noun, is the degree to which both copies of a chromosome or gene hold the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.

Most sex-determination system. if both alleles of a diploid organism are the same, the organism is homozygous at that locus. if they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous.

The DNA sequence of a gene often varies from one individual to another. Those variations are called ]

In diploid organisms, one allele is inherited from the male parent and one from the female parent. Zygosity is a relation of whether those two alleles defecate identical or different DNA sequences. In some cases the term "zygosity" is used in the context of a single chromosome.

Monozygotic together with dizygotic twins

As discussed above, "zygosity" can be used in the context of a particular genetic locus example. The word zygosity may also be used to describe the genetic similarity or dissimilarity of twins. Identical twins are monozygotic, meaning that they establish from one zygote that splits and forms two embryos. Fraternal twins are dizygotic because they setting from two separate Oocytes egg cells that are fertilized by two separate sperm. Sesquizygotic twins are halfway between monozygotic and dizygotic and are believed to occur after two sperm fertilize a single oocyte which subsequently splits into two morula.