Editing Chromosome (section)

=== In prokaryotes ===
[[Prokaryote]] species generally have one copy of each major chromosome, but most cells can easily survive with multiple copies.<ref>Charlebois R.L. (ed) 1999. ''Organization of the prokaryote genome''. ASM Press, Washington DC.</ref> For example, ''[[Buchnera (proteobacteria)|Buchnera]]'', a [[symbiont]] of [[aphid]]s has multiple copies of its chromosome, ranging from 10 to 400 copies per cell.<ref>{{cite journal | vauthors = Komaki K, Ishikawa H | title = Genomic copy number of intracellular bacterial symbionts of aphids varies in response to developmental stage and morph of their host | journal = Insect Biochemistry and Molecular Biology | volume = 30 | issue = 3 | pages = 253–8 | date = March 2000 | pmid = 10732993 | doi = 10.1016/S0965-1748(99)00125-3 | bibcode = 2000IBMB...30..253K }}</ref> However, in some large bacteria, such as ''[[Epulopiscium fishelsoni]]'' up to 100,000 copies of the chromosome can be present.<ref>{{cite journal | vauthors = Mendell JE, Clements KD, Choat JH, Angert ER | title = Extreme polyploidy in a large bacterium | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 105 | issue = 18 | pages = 6730–4 | date = May 2008 | pmid = 18445653 | pmc = 2373351 | doi = 10.1073/pnas.0707522105 | bibcode = 2008PNAS..105.6730M | doi-access = free }}</ref> Plasmids and plasmid-like small chromosomes are, as in eukaryotes, highly variable in copy number. The number of plasmids in the cell is almost entirely determined by the rate of division of the plasmid&nbsp;– fast division causes high copy number.