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Unformatted text preview: alkylation occurs at the N7, the reaction is reversible due to the presence of “suicide”
enzymes called demethylase. If alkylation occurs at the O6 position, an apurinic site in the
DNA is formed. During replication, an apurinic site may be ignored resulting in a deletion in
the daughter strand or a base is selected at random and placed in the daughter strand. Isidro C. Medina Jr. Page 3 of 7 Mutation & DNA Repair Mechanism Isidro C. Medina Jr. Page 4 of 7 Mutation & DNA Repair Mechanism DEAMINATING AGENTS
-removes amino groups from a base LYTIC CYCLE ( ) / LYSOGENIC CYCLE ( ) Example: Sodium nitrite NaNO2 (used as a preservative, color
enhancer and color fixative in bacon, smoked fish, tocino, etc.)
When ingested, sodium nitrite is converted to nitrous acid (HNO2) in
acidic conditions. Nitrous acid removes groups from adenine, guanine
and cytosine. For example, deamination of adenine results in the
formation of hypoxanthine, a structural analogue of guanine hence
may base pair with cytosine resulting in transition....
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