1595.2 Bacterial conjugationgenerally stop before the farthermost genes are transferred,resulting in their being included in fewer exconjugants.How can we explain the second unusual property ofHfr crosses, that F±exconjugants are rarely converted intoHfr or F²? When Wollman and Jacob allowed Hfr³F±crosses to continue for as long as 2 hours before dis-ruption, they found that in fact a few of the exconju-gants were converted into Hfr. In other words, the partof F that confers donor ability was eventually transmit-ted but at a very low frequency. The rareness of Hfr ex-conjugants suggested that the inserted F was transmittedas the lastelement of the linear chromosome. We cansummarize this with the following map, in which the ar-row indicates the process of transfer, beginning with O:Thus almost none of the F±recipients are converted be-cause the fertility factor is the last element transmitted,and usually the transmission process will have stoppedbefore getting that far.
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.