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pes: ①普遍性轉(zhuǎn)導(dǎo)(general transduction): 轉(zhuǎn)導(dǎo)性(假)噬菌體介導(dǎo); ②局限性轉(zhuǎn)導(dǎo)(restricted transduction): 缺陷性噬菌體介導(dǎo)。,21,第二十一頁,共四十八頁。,Generalized transduction,Definition Genetic recombination in which a DNA fragment is transferred from one bacterium to another by a phage that is now carrying donor bacterial DNA due to an error in maturation(成熟(ch233。ngsh)) during the lytic life cycle(溶菌周期). Transferred DNA: random(隨機(jī)) segment of the donor chromosomal or plasmid DNA,22,第二十二頁,共四十八頁。,普遍性轉(zhuǎn)導(dǎo)(zhuǎn dǎo)機(jī)制 (generalized transduction),轉(zhuǎn)導(dǎo)噬菌體 (假噬菌體) Results: 整合完全(w225。nqu225。n)轉(zhuǎn)導(dǎo)(complete transduction) 不整合流產(chǎn)轉(zhuǎn)導(dǎo)(abortive transduction)(多見),受體菌,供體菌,核酸酶,組裝(zǔ zhuānɡ),釋放,23,第二十三頁,共四十八頁。,Specialized transduction,Definition Genetic recombination in which a DNA fragment is transferred from one bacterium to another by a temperate phage that is now carrying donor bacterial DNA due to an error in spontaneous induction(自發(fā)誘導(dǎo)) during the lysogenic life cycle(溶原周期). Transferred DNA: specific segment (特定(t232。d236。ng)片段)of donor chromosome,24,第二十四頁,共四十八頁。,局限性轉(zhuǎn)導(dǎo)(zhuǎn dǎo)機(jī)制 (restricted transduction),bio生物素操縱子 gal半乳糖操縱子,正常(zh232。ngch225。ng)切離,偏差(piānchā)切離,缺陷噬菌體,正常噬菌體,前噬菌體,25,第二十五頁,共四十八頁。,局限性轉(zhuǎn)導(dǎo)與普遍性轉(zhuǎn)導(dǎo)的主要區(qū)別: 普遍性轉(zhuǎn)導(dǎo) 局限性轉(zhuǎn)導(dǎo) 轉(zhuǎn)導(dǎo)時(shí)間 噬菌體裂解期 溫和噬菌體溶原期 轉(zhuǎn)導(dǎo)載體 噬菌體 溫和噬菌體 轉(zhuǎn)導(dǎo)基因 供體菌染色體DNA 供體菌染色體DNA的 的任何部位基因或質(zhì)粒基因 特定部位基因 轉(zhuǎn)導(dǎo)頻率 低 107 高 104 轉(zhuǎn)導(dǎo)結(jié)果 完全轉(zhuǎn)導(dǎo) 獲得供體菌DNA特定 流產(chǎn)轉(zhuǎn)導(dǎo) 部位的遺傳(y237。chu225。n)特性,26,第二十六頁,共四十八頁。,C、溶原性轉(zhuǎn)換(zhuǎnhu224。n)(conversion),Definition 當(dāng)溫和噬菌體感染細(xì)菌時(shí),噬菌體作為供體,宿主菌染色體中整合了噬菌體的DNA片段,從而獲得新的遺傳性狀 e.g: 白喉?xiàng)U菌(gǎnjūn) (不產(chǎn)毒素),β棒狀桿菌(gǎnjūn)噬菌體