05 Mutations and DNA repair mechanism

Medina jr page 1 of 7 mutation dna repair mechanism

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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 replication TAUTOMERIC SHIFTS 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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