20xx年醫(yī)學(xué)專題—第5章--細(xì)菌的遺傳與變異(已改無錯(cuò)字)
2024-11-16 00 本頁面
【正文】 粒主要包括：F質(zhì)粒、R質(zhì)粒、Col質(zhì)粒和毒力質(zhì)粒,第三十五頁，共六十二頁。,Conjugation,Definition: Gene transfer from a donor to a recipient by direct physical contact between cells Mating（交配(jiāop232。i)） types in bacteria Donor F factor (Fertility factor) F (sex) pilus,Recipient Lacks an F factor,第三十六頁，共六十二頁。,⑴．F質(zhì)粒的接合(jiēh233。),第三十七頁，共六十二頁。,Physiological States of F Factor,Integrated (Hfr) Characteristics of Hfr x F crosses F rarely becomes Hfr while Hfr remains Hfr High transfer of certain donor chromosomal genes,第三十八頁，共六十二頁。,Physiological States of F Factor,Autonomous with donor genes (F’) Characteristics of F’ x F crosses F becomes F’ while F’ remains F’ High transfer of donor genes on F’ and low transfer of other donor chromosomal genes,第三十九頁，共六十二頁。,Mechanism of Hfr x F Crosses,DNA transfer Origin of transfer Rolling circle replication Homologous（同源(t243。nɡ yu225。n)） recombination,Pair formation Conjugation bridge,第四十頁，共六十二頁。,Mechanism of F’ x F Crosses,DNA transfer Origin of transfer Rolling circle replication,Pair formation Conjugation bridge,第四十一頁，共六十二頁。,Conjugation,Significance Gram bacteria Antibiotic resistance Rapid spread Gram + bacteria Production of adhesive material by donor cells,第四十二頁，共六十二頁。,※F+、Hfr、F`三種(sān zhǒnɡ)菌都具有性菌毛,第四十三頁，共六十二頁。,⑵．R質(zhì)粒的接合 R質(zhì)粒由耐藥傳遞因子（RTF）和耐藥決定因子（r決定因子）組成。RTF的功能與F質(zhì)粒相似，可編碼性菌毛的產(chǎn)生和通過接合轉(zhuǎn)移(zhuǎny237。)；r決定因子編碼對(duì)抗菌藥物的耐藥性，r決定因子上有多個(gè)Tn連接相鄰是造成多耐的原因。,第四十四頁，共六十二頁。,第四十五頁，共六十二頁。,Structure of R Factors,RTF Conjugative plasmid Transfer genes,R determinant Resistance genes Transposons,第四十六頁，共六十二頁。,轉(zhuǎn)導(dǎo)（transduction） 是以噬菌體為載體，將供菌的遺傳物質(zhì)轉(zhuǎn)移到受菌中去，使受菌獲得新的性狀。 普遍性轉(zhuǎn)導(dǎo) ：以毒性噬菌體和溫和噬菌體為載體，發(fā)生在裂解期，轉(zhuǎn)移的 DNA為供菌染色體上的任何(r232。nh233。)部 局限性轉(zhuǎn)導(dǎo) ：以溫和噬菌體為載體發(fā)生在溶原期
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