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Unformatted text preview: Page 1 of 7 Mutation & DNA Repair Mechanism Isidro C. Medina Jr. Page 2 of 7 Mutation & DNA Repair Mechanism SPONTANEOUS MUTATIONS
How do spontaneous mutations occur? INDUCED MUTATIONS
Induced mutations occur more frequently than spontaneous mutations. As part of normal DNA replication – DNA replication is not an error free process (proofreading ability of DNA polymerase)
Insertion/Deletion of one or more nucleotides as a result of a slippage error during DNA
o rare and reversible redistributions of electrons and protons in the structures of the
bases in the DNA. This alters their base pairing properties.
o can cause spontaneous mutation when the bases convert to their rare tautomeric forms
just as the bases are being copied during replication or transcription
o the tautomeric forms of the bases are very unstable hence short-lived
o the probability of changes due to spontaneous mutations is very low. Since changes
in the genetic make-up of a species depend on spontaneous mutations, molecular
evolution is very slow
o tautomers: keto and enol, amino and imino A. Mutations...
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