Editing Ploidy (section)

=== Diploid ===
{{redirect|Diploid|the geometrical construct|Dyakis dodecahedron}}
[[File:Human karyotype with bands and sub-bands.png|thumb|[[karyotype|Karyogram]] of a typical human cell, showing a diploid set of 22 [[Homologous chromosome|homologous]] [[autosomal]] chromosome pairs. It also shows both the female (XX) and male (XY) versions of the two [[sex chromosome]]s (at bottom right), as well as the [[human mitochondrial genetics|mitochondrial genome]] (to scale at bottom left). {{further|Karyotype}}]]
Diploid describes a cell or nucleus which contains two copies of genetic material, or a complete set of chromosomes, paired with their homologs (chromosome carrying the same information from the other parent).<ref>{{cite web |title=Diploid Definition |url=https://biologydictionary.net/diploid/ |website=Biology Dictionary |access-date=28 January 2025}}</ref>
'''Diploid''' cells have two [[Homologous chromosome|homologous]] copies of each [[chromosome]], usually one from the [[mother]] and one from the [[father]]. All or nearly all mammals are diploid organisms. The suspected tetraploid (possessing four-chromosome sets) plains viscacha rat (''[[Tympanoctomys barrerae]]'') and golden viscacha rat (''[[Pipanacoctomys aureus]]'')<ref name="Gallardo-2006">{{cite journal |vauthors=Gallardo MH, González CA, Cebrián I | title=Molecular cytogenetics and allotetraploidy in the red vizcacha rat, ''Tympanoctomys barrerae'' (Rodentia, Octodontidae)] | journal=Genomics | volume=88 | issue=2 | pages=214–221 | year=2006 | pmid=16580173 | doi=10.1016/j.ygeno.2006.02.010 | doi-access=free }}</ref> have been regarded as the only known exceptions (as of 2004).<ref>{{cite journal | author=Gallardo M. H. | year=2004 | title=Whole-genome duplications in South American desert rodents (Octodontidae) | journal=Biological Journal of the Linnean Society | volume=82 | issue= 4| pages=443–451 | doi=10.1111/j.1095-8312.2004.00331.x |display-authors=etal| doi-access=free | hdl=11336/102012 | hdl-access=free }}</ref> However, some genetic studies have rejected any [[polyploid]]ism in mammals as unlikely, and suggest that amplification and dispersion of repetitive sequences best explain the large genome size of these two rodents.<ref name="Svartman-2005">{{cite journal |doi=10.1016/j.ygeno.2004.12.004 |title=Molecular cytogenetics discards polyploidy in mammals |year=2005 |last1=Svartman |first1=Marta |last2=Stone |first2=Gary |last3=Stanyon |first3=Roscoe |journal=Genomics |volume=85 |issue=4 |pages=425–430 |pmid=15780745}}</ref> All normal diploid individuals have some small fraction of cells that display [[polyploid]]y. [[Human genome|Human]] diploid cells have 46 chromosomes (the [[Somatic (biology)|somatic]] number, ''2n'') and human haploid [[gametes]] (egg and sperm) have 23 chromosomes (''n''). [[Retrovirus]]es that contain two copies of their RNA genome in each viral particle are also said to be diploid. Examples include [[human foamy virus]], [[human T-lymphotropic virus]], and [[HIV]].<ref>{{Cite web |url=http://web.uct.ac.za/depts/mmi/jmoodie/hiv2.html |title=Human Retroviruses |access-date=2008-05-14 |archive-url=https://archive.today/20030330094545/http://web.uct.ac.za/depts/mmi/jmoodie/hiv2.html |archive-date=2003-03-30 |url-status=dead }}</ref>