Figure 14.25 Nature of mutation Consequences Substitutions of individual bases create mismatched pairs that may be corrected by replacing one base; if uncorrected they sine U-G replaces C-G cause a mutation in one daughter duplex N N Corrected by remowngu HH HH Purine pair distorts duplet o Replication errors Cytosine Adenine N脱氨基 NH2 O H H H N N Deamination H N O H N O Cytosine Uracil Fig. 21- Deamination of cytosine to uracil