Transition (genetics)

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Not to be confused with the evolutionary concept of a transitional fossil.
Definition of transitions and transversions.

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.

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. ↑ Mutations & Mutagenesis
  3. ↑ 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. 

External links

Mechanisms of mutation
Mutation with respect to structure
Large-scale mutation
  • Chromosomal translocations
  • Chromosomal inversions
Mutation with respect to overall fitness
  • Deleterious mutation
  • Advantageous mutation
  • Neutral mutation
  • Nearly neutral mutation
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