第5章 DNA损伤和修复.doc

文档介绍：Chapter 5 DNA damage and repair

诱变
DNA损伤
DNA修复
:
熟悉DNA损伤的原因、类型
掌握DNA修复的方式
Mutagenesis
DNA damage
DNA Repair
Mutagenesis (诱变)
The reasons of mutation
Types of mutations
Mutagens (诱变剂)
mutagenesis (诱变)
Mutagenesis (诱变)
Mutation (突变) = Permanent, heritable alterations in the base sequence of a DNA molecule(是DNA碱基序列水平上永久性的、可遗传的变化)
The reasons of mutation
Spontaneous errors(自发性错误): in DNA replication or meiotic bination
Mutagen (诱变物): A consequence of the damaging effects of physical or chemical mutagens on DNA
Mutagen= mutation causing agent
Essentially all mutagens are carcinogens(致癌物)
Most carcinogens are mutagens
Types of mutations
Multisite(多位点):
-Cause gross(严重的) chromosome abnormalities(畸形);
-Involve large regions of DNA ;
-Arise during meiosis(在减数分裂期发生)
Point mutations(点突变)
-Involve only one or a few nucleotides;
- Arise during DNA replication
-Require two errors :1)An error during DNA replication;2)Failure to correct that error
Types of point mutations
Inversions: ACBDEF
Duplications ABCDEEF
Deletions: ABCD-F
Insertions: ABCDSEF
Substitutions: ATCDEF
Types of point mutations
The phenotypic effect of point mutation(点突变的表型效应)
Missense mutation(错义突变): 碱基序列的改变引起了产物氨基酸序列的改变。
Nonsense mutation(无义突变) : 某个碱基的改变使代表某种氨基酸的密码子变为蛋白质合成的终止密码子( stop codon, TAG, TAA, TGA)。