In molecular biology, transversion refers to the substitution of a purine for a pyrimidine or vice versa Mutations & Mutagenesis. It can only be reverted by a spontaneous reversion. Because this type of mutation changes the chemical structure dramatically, the consequences of this change tend to be more severe and less common than that of transitions.Transversions can be caused by ionizing radiation and alkylating agents.… (More on Transversion)