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Transition (genetics)

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This is an old revision of this page, as edited by 2pou (talk | contribs) at 16:07, 15 June 2022 (Changing short description from "A DNA mutation that exchanges two purine nucleotides (A to G, and vice versa) or two pyrimidine nucleotides (C to T, and vice versa)" to "DNA mutation that exchanges two nucleotides"). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

For other uses, see Transition.
Illustration of a transition: each of the 4 nucleotide changes between purines or between pyrimidines (in blue). The 8 other changes are transversions (in red).

Transition, in genetics and molecular biology, refers to 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. Although there are twice as many possible transversions, transitions appear more often in genomes, possibly due to the molecular mechanisms that generate them.[2]

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.

See also

References

  1. ^ 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.
  2. ^ 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.
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