Figure 1.
Scheme that illustrates the difference between mutation rate and mutant frequency. Residue U (on the left), A (in the middle), and C (on the right) can be misread to incorporate a G (on the left), C (in the middle), or A (on the right) in the complementary strand at a rate of 10−4 substitutions per nucleotide in all cases. The replicative capacity of the newly G, C, and A templates determines the different mutant frequencies with 10−3, 10−4, and 10−5 substitutions per nucleotide, respectively.