基因工程2-2.ppt

11-17-2004 Molecular Biology Genetic Engineering Introduction++ Mutation and Mutagenesis变异发生++++ Gene Expression++++ Bacteriophage++ Plasmids, Transposon and Vectors+++ rDNA Cloning ++++ PCR Technology ++++ Medical Forensic Application++ Mutation and Repair DNA faces a constant challenge. Damages during DNA replication, if not corrected, could lead to permanent永久的change-mutation Most mutations are potentially潜在地dangerous危险的, so DNA repair system needed for correcting replication errors and for eliminating消除damage to DNA caused by environmental agents and intracellular chemicals Chapter 2: Mutation and Mutagenesis Term and definition Types of mutations+ Mutagenesis Mutagen Reversion复原 DNA Repair Mechanisms Mutagenesis in vitro体外+ I.Term and definition1 Mutant: an organism or a gene that is different from the normal or wild type, or an organism in which either the base sequence of the DNA or the phenotype has been changed + as wild type, and - as a mutant Mutation: any heritable可遗传的change in the base sequence of a DNA molecule. The most common type of change is a substitution置换, addition, or deletion删除of one or more bases I.Term and definition2 Spontaneous mutation: mutation occurs in nature without the addition of a mutagen and the resulting mutant is spontaneous mutant. It may arise through (a) errors in DNA replication or (b) spontaneous alteration of a nucleotide within an existing DNA molecule Induced mutation: the process is caused by a mutagen Mutagenesis: the process过程of producing a mutation I.Term and definition3 Mutagen: a physical or chemical agent that causes mutations to occur (or increases the frequency of their occurrence) Hot spot: a site is represented by as many as 100 times the typical number of mutation Mutator gene增变基因: a gene that, when presents in a mutant state, causes mutations to appear very frequently in other genes throughout the genome II. Types of Mutations Mutation by Base Number Change Base substitution Frameshift移码Mutation Muta