Point mutations are 

Point mutations are the mutations due to base substitutions. In this, a purine or pyrimidine may be substituted by another purine or pyrimidine (transition mutation) or a purine is substituted by a pyrimidine or pyrimidine is substituted by purine (transversion mutations). Deletion or addition of a gene in a chromosome are chromosomal mutations. Mutations due to insertion or deletion of base pair are a type of gene mutations which may result in the frame shift.