05 Mutations and DNA repair mechanism

If alkylation occurs at the n7 the reaction is

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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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