In a mutational event, when adenine is replaced by guanine, it is a case of -
A
Transcription
B
Transition
C
Transversion
D
Frameshift mutation
The answer is B.
Solution
Point mutations in which one base is substituted for another are of two types. Transition: a purine is replaced by another purine (A to G or G to A), or a pyrimidine by another pyrimidine (C to T or T to C). Transversion: a purine is replaced by a pyrimidine or vice versa (e.g. A to T, G to C). Adenine and guanine are both purines, so replacing adenine by guanine is a transition. A frameshift mutation is the insertion or deletion of bases, and transcription is not a mutation at all. So it is a case of transition.
ConceptTransition versus transversion
Molecular Basis of Inheritance in past papers
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