a point mutation comprising the substitution of a purine by pyrimidine is called transition translocation deletion transversion

Transitions: replacement of apurinebase with anotherpurineor replacement of apyrimidinewith another pyrimidine
Transversions: replacement of a purine with a pyrimidine or vice versa.
There is a systematic difference in mutation rates fortransitions(Alpha) andtransversions(Beta). Transition mutations are about ten times more common than transversions.