Molecular Basis of Inheritance Question 107

107. Out of A-T, G-C pairing, bases of DNA may exist in alternate valency state owing to arrangement called

(a) analogue substitution

(b) tautomerisational mutation

(c) frame-shift mutation

(d) point mutation

Show Answer

Answer : b

Hints & Solution

(b) The tautomer forms of nitrogen bases are imino-tautomer instead of amino group (e.g. cytosine, adenine) or enol instead of the keto group (e.g. thymine, guanine). Tautomers are organic compounds that are interconvertible by a chemical reaction called tautomerisation. The concept of tautomers that are interconvertible by tautomerisations is called tautomerism. Tautomerism is a special case of structural isomerism and can play an important role in non-canonical base pairing in DNA and especially RNA molecules.



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