Substitution C Silent mutation Missense mutation Nonsense mutation TGT→ TGC TGT→ TGG TGT→TGA s→>T Cys→>Sop In the substitution mutation. one or more nucleotides are substituted by the same number of different nucleotides. In most cases, only one nucleotide is changed. Based on the change in the nucleotide type, the substitution mutation may be divided into transition and transversion mutations. Based on the consequence of mutation, the substitution mutation may be grouped into silent, missense and nonsense mutations
Substitution In the substitution mutation, one or more nucleotides are substituted by the same number of different nucleotides. In most cases, only one nucleotide is changed. Based on the change in the nucleotide type, the substitution mutation may be divided into transition and transversion mutations. Based on the consequence of mutation, the substitution mutation may be grouped into silent, missense and nonsense mutations
Deletion 141142143144145 GCC BT TTT GGC CTT TCA Gac ata tac caa Delete T Delete AT 141142143144 鬥3331r31 GCC ATT TIG GCC TT TCA GAC ATA CCA 329 CCA emnamr 332333 168 170171172 GAC CGA GAA GAT AGT CTT Delete TTG Delete ATAG 329330331332 168169170171 CC CTT GAC CGA GAA ATA GTC TT
Deletion
Exon Skipping Exon 、.Exon2 exon 3 T AGI T AGI Intron 1 Intron 2 a to c mutation內含子序列政变, 启动子结合蛩白无 法正常识别 Exon M…“…· 上n2 Exon 3 ST AG Intron 1 Intron 2
Exon Skipping 内含子序列改变， 启动子结合蛋白无 法正常识别
复制的忠实性 ◆DNA复制的错配率极低 ◆保证DNA复制高度忠实性的机制有 ■只有当进入活性位点的核苷酸与模板核苷酸 满足正确的碱基配对原则时,DNA聚合酶才 能够将其掺进来 ■聚合醯的3′-5外切酶活性可以检测出偶发 错误,并在下一个核苷酸掺入前从3端去掉 错配的核苷酸,从而保证碱基的正确插入;
复制的忠实性 DNA复制的错配率极低 保证DNA复制高度忠实性的机制有： ◼ 只有当进入活性位点的核苷酸与模板核苷酸 满足正确的碱基配对原则时，DNA聚合酶才 能够将其掺进来； ◼ 聚合酶的3’－5’外切酶活性可以检测出偶发 错误，并在下一个核苷酸掺入前从3’端去掉 错配的核苷酸，从而保证碱基的正确插入；
物理诱变剂 ◆高能离子化辐射(Ⅹ射线) 会引起目标分子失去电子,导致DNA发生广 泛的化学变异,包括断链、碱基或五碳糖的 损伤; ◆非离子化辐射 ■引起在目标分子内的分子振动,或促进电子 进入较高能级。导致形成新的化学键 紫外线—可导致相邻嘧啶碱基产生二聚体
物理诱变剂 高能离子化辐射（X射线） ◼ 会引起目标分子失去电子，导致DNA发生广 泛的化学变异，包括断链、碱基或五碳糖的 损伤； 非离子化辐射 ◼ 引起在目标分子内的分子振动，或促进电子 进入较高能级，导致形成新的化学键 紫外线—可导致相邻嘧啶碱基产生二聚体