Centisome
Acentisomeis a unit of length defined as one percent of the length of a particularchromosome.[1]This course unit of physicalDNAlength began to be used in the early exploration of genomes through molecular biology before the resolution of thenucleic acid sequencesof chromosomes was possible.
One of the main uses for this unit was for describing thelocusof a gene by giving a distance in centisomes from a reference point on the chromosome. For instance, when the complete genome of the bacteriumEscherichia coliwas finally completed in 1997, it was presented with a scale given in centisomes (as well as one inkilobases).[2]Since bacterial chromosomes arecircular,the reference point cannot be an end of the DNA molecule, but must be some point that has some easily determinable unique characteristic. Often this point is theorigin of replication,although forE. coliit is the origin of transfer duringconjugation.[3]Hence, the reference point for centisome positions is simply a convention established for each individual species of organism.
For the most part, modern scientific literature uses "centisome" as part of a shorthand way of referring to a particular region of interest on the chromosome of particular organisms. For instance, much research has been done on the "Centisome 63" area of the chromosomes ofSalmonellaspecies.[4][5]
References
[edit]- ^Peter D. Karp; Monica Riley (2009-01-11),Representations of Metabolic Knowledge(PDF)
- ^Blattner, FR; Plunkett G, 3rd; Bloch, CA; Perna, NT; Burland, V; Riley, M; Collado-Vides, J; Glasner, JD; Rode, CK; Mayhew, GF; Gregor, J; Davis, NW; Kirkpatrick, HA; Goeden, MA; Rose, DJ; Mau, B; Shao, Y (5 September 1997). "The complete genome sequence of Escherichia coli K-12".Science.277(5331): 1453–62.doi:10.1126/science.277.5331.1453.PMID9278503.
{{cite journal}}:CS1 maint: numeric names: authors list (link) - ^"Escherichia coli K-12 substr. MG1655 oriC".biocyc.org.EcoCyc.Retrieved4 April2021.
For historical reasons, the numbering of E. coli's circular chromosome does not start at the origin of replication, but at the origin of transfer during conjugation.
- ^Galán, JE (April 1996). "Molecular genetic bases of Salmonella entry into host cells".Molecular Microbiology.20(2): 263–71.doi:10.1111/j.1365-2958.1996.tb02615.x.PMID8733226.S2CID8677354.
- ^"Google Scholar search for 'Centisome 63'".scholar.google.
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