Transition versus Transversion mutations
mutations are of two types. Transitions are
of two-ring purines (A G)
of one-ring pyrimidines
therefore involve bases of similar shape.
are interchanges of purine for
which therefore involve exchange of one-ring
and two-ring structures.
Although there are twice as many possible transversions, because of
molecular mechanisms by which
they are generated, transition mutations are generated at higher
than transversions. As well, transitions are less likely to
result in amino acid substitutions (due to "wobble"), and are therefore
more likely to persist as "silent substitutions" in populations as single nucleotide