Transition (genetics)

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Definition of transitions and transversions.

In genetics, a transition is a point mutation that changes a purine nucleotide to another purine (AG) or a pyrimidine nucleotide to another pyrimidine (CT). 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

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  2. Mutations & Mutagenesis
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External links

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