细菌可以通过以下不同的方式获得外源遗传物质 : A 转化 . 即细菌通过其细胞膜摄取周围供体的 DNA 片段,并将此外源 DNA 片段通过 重组参入自己的染色体组过程 B 接合 . 即遗传物质从供体 —“ 雄性 ” 转移到受体 —“ 雌性 ” 的过程。接合主要是通过 F 因子起作用的。作用的方式有三种: a. F+ × F– ; b. Hfr × F– ; c. F’ × F– C 转导 . 即以噬菌体为媒体所进行的细菌遗传物质重组的过程
【单选题】听力原文: Prison service staff here in Britain has been severely criticized in an official report for escape of five Iraqi prisoners and an armed robber from Whitewall Prison in Kenbershire. Bomb-making e...
【单选题】听力原文: Prison service staff in Britain have been severely criticized in an official report for the escape of five IRA prisoners and an armed robber from White mall Prison, Cambridge shire. Bomb-making ...
【单选题】听力原文:Thank you for calling the Britain information service. If you'd like information about train times, please press 1. If you' d like to book a ticket, please press 2. If you want information about ...