haploidisen

Haploidisen, commonly translated as haploid in English, denotes a cellular or organismal state characterized by a single complete set of chromosomes (n). A haploid cell contains one chromosome from each homologous pair, whereas a diploid cell carries two. In humans, for example, gametes—the sperm and egg—are haploid and contain 23 chromosomes.

Meiosis is the process that reduces chromosome number from diploid to haploid, generating genetic variation through recombination and independent assortment. Fertilization then restores diploidy by fusing two haploid gametes into a diploid zygote.

Life cycles vary with ploidy. Some fungi and many algae are haplontic or haploid-dominant, with multicellular stages that are haploid and transient diploid stages. In higher plants and animals, the dominant multicellular stage is typically diploid, while haploid cells occur as gametes or as brief, unicellular phases in reproduction. In plants, this alternation of generations includes a haploid gametophyte stage and a diploid sporophyte stage.

Other related terms include polyploidy (more than two chromosome sets) and aneuploidy (abnormal chromosome number). Haploidisen is central to cytogenetics, genetics, and evolutionary biology, providing a framework for studying inheritance, recombination, and population genetics.