Biochemistry Metabolism of nucleic acids a99b7877 "Transition mutation" occurs in A A - G B A - C C A - T D D - G High-Yield Explanation Replacement of purine by another purine (A to G or G to A ) or pyrimidine by pyrimidine (T to C or C to T ) is called transition mutationRef: DM Vasudevan, 7th edition, page no: 612