Transition (genetics)
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- Not to be confused with the evolutionary concept of a transitional fossil.
In genetics, a transition is a point mutation that changes a purine nucleotide to another purine (A ↔ G) or a pyrimidine nucleotide to another pyrimidine (C ↔ T). Approximately two out of three single nucleotide polymorphisms (SNPs) are transitions.[1]
Transitions can be caused by oxidative deamination and tautomerization.[2] Although there are twice as many possible transversions, transitions appear more often in genomes, possibly due to the molecular mechanisms that generate them[3].
5-Methylcytosine is more prone to transition than unmethylated cytosine, due to spontaneous deamination. This mechanism is important because it dictates the rarity of CpG islands.
[edit] See also
[edit] References
- ^ Collins DW, Jukes TH (April 1994). "Rates of transition and transversion in coding sequences since the human-rodent divergence". Genomics 20 (3): 386–96. doi:10.1006/geno.1994.1192. PMID 8034311. http://linkinghub.elsevier.com/retrieve/pii/S0888-7543(84)71192-X.
- ^ Mutations & Mutagenesis
- ^ Ebersberger I, Metzler D, Schwarz C, Pääbo S (June 2002). "Genomewide comparison of DNA sequences between humans and chimpanzees". Am. J. Hum. Genet. 70 (6): 1490–7. doi:10.1086/340787. PMC 379137. PMID 11992255. http://linkinghub.elsevier.com/retrieve/pii/S0002-9297(07)60701-0.
[edit] External links
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