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Question
Which of the following agents causes mutation through deamination?
Which of the following agents causes mutation through deamination?
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Solution
The correct option is E HNO2
5-bromouracil (5BU) is a pyrimidine analogue of thymine which tautomerizes more readily than thymine does; the enol form of 5-bromouracil pairs with guanine and thereby causes the transition. 2-aminopurine is a purine analogue that acts like adenine and forms two hydrogen bonds with thymine. But its enol form pair with cytosine which means that its keto form replaces adenine and its enol form replaces guanine thereby causing transition mutations. Methane sulphonate cause mutation by base substitution; it alkylates guanine into 7-alkyl guanine which pairs with thymine instead of cytosine thus producing base pair mistake during DNA replication. X-ray causes chromosomal aberrations by introducing chromosomal breaks, alteration of nitrogenous bases, or by initiating a chain of chemical reactions. UV absorption induces dimerization of thymine in DNA which disrupts the hydrogen bonding between bases by forming bumps in the DNA and on the complementary strands. Nitrous acid converts cytosine to uracil, adenine to hypoxanthine by replacing their amino groups with keto groups. As we know that uracil pairs with adenine, whereas its progenitor, cytosine, normally pairs with thymine; hypoxanthine pairs with cytosine, whereas its progenitor, adenine, normally pairs with thymine; thereby causing transition mutations. Nitrogen mustards (NMs) replace chloride by amine nitrogen and form aziridinium rings which in turn alkylates DNA. Thus, the correct answer is option E.
5-bromouracil (5BU) is a pyrimidine analogue of thymine which tautomerizes more readily than thymine does; the enol form of 5-bromouracil pairs with guanine and thereby causes the transition. 2-aminopurine is a purine analogue that acts like adenine and forms two hydrogen bonds with thymine. But its enol form pair with cytosine which means that its keto form replaces adenine and its enol form replaces guanine thereby causing transition mutations. Methane sulphonate cause mutation by base substitution; it alkylates guanine into 7-alkyl guanine which pairs with thymine instead of cytosine thus producing base pair mistake during DNA replication. X-ray causes chromosomal aberrations by introducing chromosomal breaks, alteration of nitrogenous bases, or by initiating a chain of chemical reactions. UV absorption induces dimerization of thymine in DNA which disrupts the hydrogen bonding between bases by forming bumps in the DNA and on the complementary strands. Nitrous acid converts cytosine to uracil, adenine to hypoxanthine by replacing their amino groups with keto groups. As we know that uracil pairs with adenine, whereas its progenitor, cytosine, normally pairs with thymine; hypoxanthine pairs with cytosine, whereas its progenitor, adenine, normally pairs with thymine; thereby causing transition mutations. Nitrogen mustards (NMs) replace chloride by amine nitrogen and form aziridinium rings which in turn alkylates DNA. Thus, the correct answer is option E.
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