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Post nucleotide insertion step during DNA replication in which the resulting base pairing is checked for accuracy, with the newly added nucleotide replaced if need be.
Proofreading represents one of a number of layers that contribute to the fidelity of DNA replication, that is, the low base misincorporation rates usually seen along with the low low mutation rates generally observed.
Proofreading is notably absent during RNA polymerization, greatly contributing to the error rate associated with that process, as most notably seen with RNA viruses such as HIV, i.e., human immunodeficiency virus, the cause of AIDS. That is, RNA-based genetic material tends to be riddled in transcription errors which are associated, in part, to the lack of proofreading among RNA polymerases (and reverse transcriptases)
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