(3)移码突变( Frame- shift mutations 经常发生在重复序列区。移码突变的模型: Addition Deletion 5CGTTTT 5. CTGAGAGA a) 3GCAAAAACGTAC (d) 3 GACTCTCTCTCTCTGCA 5C TTT 5.CTGAGAGA 3GCAAAAACGTAC 3 GACTCTCTCTGCA 5C T TTTTGCTAG 5. CTGAGAGAGACGT (c) 3GCAAAAACGTAC 3 GACTCTCTCTGCA（3）移码突变(Frame－shift mutations) 经常发生在重复序列区。移码突变的模型： 5 , CGTTTT 3 , GCAAAAACGTAC 5 , C TTT 3 , GCAAAAACGTAC 5 , C T TTTTGCTAG 3 , GCAAAAACGTAC GT GT (a) (b) (c) 5,CTGAGAGA 3,GACTCTCTCTCTCTGCA 5,CTGAGAGA 3,GACTCTCTCTGCA 5,CTGAGAGAGACGT 3,GACTCTCTCTGCA CT CT Addition Deletion (d) (e) (f)