紫外诱导的DNA结构变化 H Kink CHs H H Figure 12-33 Formation of thymine dimers in- duced by UV light. ( a) The reaction on the left re- -OH sults in the formation of a cyclobutyl ring involving C-5 and C-6 of each thymine residue, just as UV CH light will induce the formation of cyclobutane fror two molecules of ethylene, An alternative light Cyclobutane thymine dimer 6-4 Photoproduct induced reaction between adjacent thymines results in a linkage between C-6 of one residue and C-4 of its neighbor, as shown on the right. A bend or kink is introduced into the DNA on formation of a cyclo butane thymine dimer (b)
紫外诱导的DNA结构变化
DNA Repair QAll Cells Have Multiple DNA Repair Systems ■ Direct repair--复活 EXcision repair ◆ Base-excision repair Nucleotide-excision repair a Mismatch repair
DNA Repair All Cells Have Multiple DNA Repair Systems ◼ Direct repair----光复活 ◼ Excision repair Base-excision repair Nucleotide-excision repair ◼ Mismatch repair