Ans: DNA Mutations are random changes in the DNA’s base sequence. These changes can be large which can cause structural changes in chromosomes or they can be small scale where only a single nucleotide or base is altered. Transition mutation refers to a point mutation when a purine nucleotide changes to another purine (AG) or there is a change in one pyrimidine nucleotide to another (CT).In transversion, either a purine is substituted for a pyrimidine or a pyrimidine for a purine.