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Eduncle posted an MCQ
December 30, 2019 • 17:50 pm 0 points
  • CSIR NET
  • Life Sciences

A chemist synthesizes three new chemical compounds in the laboratory and names them as X, Y and Z. After analysis mutagenic potential of all these compounds, the geneticist observed that all are highly mutagenic. The geneticist also tested the potential of mutations induced by these compounds to be mutations induced by these compounds to be reversed by other known mutagens and obtained the following results.

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    Eduncle Best Answer

    Treatment of cytosine with nitrous acid produces uracil which pairs with adenine to produce a CG-to-TA transition mutation during replication. Likewise, nitrous acid modifies adenine to produce hypoxanthine, a base that pairs with cytosine rather than thymine, which results in an AT-to-GC transition mutation. So transition mutations can be reverted by Nitrous acid. Mutations induced by hydroxylamine can only be CG-to-TA transitions. So only AT-GC transitions can be reverted by hydroxylamine. Intercalating agents such as proflavin, acridine, and ethidium bromide can cause either additions or deletions, frameshift mutations induced by intercalating agents can be reverted by a second treatment with those same agents. So single base deletion induced by Z can be reverted by acridine orange.

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