It's more common to happen transitions( even though there are less possibilities) because of the shape of the molecules.
Transitions exchange bases of similar shape (swaps a purine for a purine or a pyrimidine for a
pyrimidine), whereas transversions exchange bases of different shape( swaps a purine for a pyrimidine (or
vice versa)).
A and G are
purines, C and T are pyrimidines.
possible
transversions A-C, A-T, T-G,
G-C
transitions are
A-G or C-T
answer: AG or CT pairs
