上泽充通大￥ Shanghai Jiao Tong University 1896 1920 1987 2006 How can a bacterium change itself by taking genes from other bacteria? Lecture 10-2 Bacterial genetics II.Genetic Exchange In Prokaryotes Chapter 1o in BROCK BIOLOGY OF MICROORGANISMS IJIAO TONG UN Chen Feng School of Life Science and Technology, Shanghai Jiao Tong University http://micro.sjtu.edu.cn
1896 1920 1987 2006 Lecture 10-2 Bacterial genetics II. Genetic Exchange In Prokaryotes How can a bacterium change itself by taking genes from other bacteria? Chen Feng School of Life Science and Technology, Shanghai Jiao Tong University http://micro.sjtu.edu.cn Chapter 10 in BROCK BIOLOGY OF MICROORGANISMS
10.6 Genetic recombination遗传重组 The physical exchange of genetic material between genetic elements Genetic elements: ·Chromosomes ·Plasmids ·Viruses Chen Feng,Shanghai Jiao Tong University
Chen Feng, Shanghai Jiao Tong University 10.6 Genetic recombination遗传重组 The physical exchange of genetic material between genetic elements Genetic elements: • Chromosomes • Plasmids • Viruses
Molecular Events in Homologous Recombination同源重组 General or homologous recombination同源重组 Genetic exchange between homologous DNA sequences from two different sources ©Homologous DNA sequences同源序列 Having the same or nearly the same sequence Extremely important for all organisms重要性 .25 genes involved in E.coli Several redundant pathways.Therefore,if one pathway is inhibited,.another may supply necessary functions..有数条替代 途径备用 Chen Feng,Shanghai Jiao Tong University
Chen Feng, Shanghai Jiao Tong University Molecular Events in Homologous Recombination 同源重组 General or homologous recombination同源重组 • Genetic exchange between homologous DNA sequences from two different sources Homologous DNA sequences同源序列 • Having the same or nearly the same sequence Extremely important for all organisms重要性 • 25 genes involved in E. coli • Several redundant pathways. Therefore, if one pathway is inhibited, another may supply necessary functions.有数条替代 途径备用
Donor DNA Endonuclease nicks DNA Molecular mechanism of genetic recombination Nick 0 Binding of SSB protein SSB protein Processes: 00000 Recipient DNA 1.Nick formation Strand RecA invasion 2.Strand invasion protein 000 3.Heteroduplex formation 源双链核酸的形成 Development of cross-strand exchange 4.Resolution of heteroduplex complex (SSB)single-stranded binding protein Resolution Resolution at sites at Vsites Patches Splices 2012 Pearson Education,Inc
Molecular mechanism of genetic recombination Processes: 1. Nick formation 2. Strand invasion 3. Heteroduplex formation异 源双链核酸的形成 4. Resolution of heteroduplex complex (SSB) single-stranded binding protein
Detection of recombination DNA from Trp*cells Agar lacking Agar lacking tryptophan tryptophan Trp-cells No growth Trpcells Recombinants form colonies A selective medium can be used to detect rare genetic recombinants among a large population of nonrecombinants.On the selective medium only the rare recombinants form colonies
Chen Feng, Shanghai Jiao Tong University Detection of recombination A selective medium can be used to detect rare genetic recombinants among a large population of nonrecombinants.On the selective medium only the rare recombinants form colonies