definição e significado de Transition_(genetics)

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.

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.

External links

Diagram at mun.ca

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Mutation

Mechanisms of mutation

Insertion · Deletion · Substitution (Transversion, Transition)

Mutation with respect to structure

Point mutation	Nonsense mutation · Missense mutation · Silent mutation · Frameshift mutation · Dynamic mutation

Large scale mutation	Chromosomal translocations · Chromosomal inversions

Mutation with respect to overall fitness

Deleterious mutation · Advantageous mutation · Neutral mutation · Nearly neutral mutation

Definição e significado de Transition_(genetics)

Definição

Transition (genetics)

See also

References

External links