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1、Genetic Analysis in Bacteria and Bacteriophages 细菌与噬菌体遗传structure of bacterial genomes mechanisms by which bacteria transfer genes between cells of the same species mechanisms by which bacteria transfer genes between bacterial cells and bacterial viruses Geneticists can use their knowledge of bacter
2、ial genetics in general and of various forms of bacterial gene transfer in particular to identify, map, and characterize the genes that contribute to biological process.5.1 Plasmid patterns 质粒类型5.2 Transfer of genes between bacteria 细菌间基因的传递5.2.1 Transfer by conjugation （ 结合传递）5.2.2 Three transfer t
3、ypes (F+, F-, Hfr, F cells)5.2.3 Interrupted mating experiment 中断杂交技术5.3 Transfer of genes between bacterium and bacterial viruses 细菌与噬菌体间基因的传递5.3.1 Bacteriophage and its properties5.3.2 Generalized transduction （普通转导）5.3.3 Specialized transduction （特定转导）5.3.4 Recombination in bacteriaAdvantages：1.
4、Rapid reproduction, short life-span and large amount 2. Small genetic material, simple cell structure3. Simple DNA structure, naked, helix and circular DNA 4. Monoploid DNAPlasmids are chromosome-like structures found in bacterial cells, but which are not essential to bacterial growth. Some can move
5、 from one bacterium to another. The best studied is the F plasmid. This is an episome, an element that can replicate either independently or integrate into the bacterial chromosome.5.1 Plasmid patternsE.coli encodes all the enzymes it needs for amino-acid and nucleotide biosynthesis, it can grow in
6、minimal media, which contain glucose as the only source of carbon and energy, and inorganic salts as the source of the other elements that compose bacterial cells.遗传物质的分布： E.coli: 大环DNA 主染色体 4106bp质粒 小染色体，大环DNA的0.5%2% ，约40005000bpv infectious：from donor strain to recipient 从一个细菌（供体菌）转移到另一个不含质粒的受体菌中
7、non-infectious: 不能传递 v replicable: isolated from chromosome 独位于染色体之外 combined: integrated into main chromosome and disengaged again 插入到主染色体上, 条件改变可脱离 v F plasmid: F+ - 供体菌(雄性菌), 膜上有性须, 可转移F- - 受体菌 (雌性菌), 无性须 R plasmid: antibiotic resistance (抗药性质粒)Plasmid pattern5.1 Plasmid patterns 质粒类型5.2 Transfer
8、 of genes between bacteria 细菌间基因的传递5.2.1 Transfer by conjugation （ 结合传递）5.2.2 Three transfer types (F+, F-, Hfr, F cells)5.2.3 Interrupted mating experiment 中断杂交技术5.3 Transfer of genes between bacterium and bacterial viruses 细菌与噬菌体间基因的传递5.3.1 Bacteriophage and its properties5.3.2 Generalized transdu
9、ction （普通转导）5.3.3 Specialized transduction （特定转导）5.3.4 Recombination in bacteriaChapter 5 Genetic Analysis in Bacteria and Bacteriophages 第五章 细菌与噬菌体遗传5.2 Transfer of genes between bacteria Focus on E.coli: the most studied and best understood species of bacteria is E.coli, a common inhabitant of ver
10、tebrate intestines. E.coli cells can grow in the complete absence of oxygenthe condition found in the intestines. 5.2.1 Transfer by conjugation （ 结合传递）(营养缺陷型菌 原养型 完全培养基)Strain A: met- bio- thr+ leu+ thi+ Strain B: met+ bio+ thr- leu- thi- Minimal mediumA met- bio- thr+ leu+ thi+B met+ bio+ thr- leu-
11、 thi-met+ bio+ thr+ leu+ thi+coloniesFounded by electronic microscope:Conjugation tube produced between two strainsABStreptomycin (链霉素) treatment on A and B separately A x BRestrained reproductioncolonies A x BRestrainedreproductionno colony A Bdonor strain recipient F+ F-5.1 Plasmid patterns 质粒类型5.
12、2 Transfer of genes between bacteria 细菌间基因的传递5.2.1 Transfer by conjugation （ 结合传递）5.2.2 Three transfer types (F+, F-, Hfr, F cells)5.2.3 Interrupted mating experiment 中断杂交技术5.3 Transfer of genes between bacterium and bacterial viruses 细菌与噬菌体间基因的传递5.3.1 Bacteriophage and its properties5.3.2 Generaliz
13、ed transduction （普通转导）5.3.3 Specialized transduction （特定转导）5.3.4 Recombination in bacteriaChapter 5 Genetic Analysis in Bacteria and Bacteriophages 第五章 细菌与噬菌体遗传5.2.2 Three transfer types: 1) 游离态F质粒F+ F- Low recombination between main chromosome 主染色体之间重组率低 F- F+ flash2) 结合态F质粒 F+ integrated into main
14、DNA (Hfr strain)F- HIGH cross-overs and recombination between main DNA F- F-flashF-Hfr3) F质粒 When the F plasmid is excised from the bacterial chromosome it sometimes incorporates part of the chromosome into its own structure - FHfr菌株质粒从主染色体脱离时携带部分主染色体基因形成的 游离质粒 - F flash Hfr F F- F integration sexduction (性导) Low frequency F- F HfrF1)2)3)I
