notes 2-23 - An F+ x F- mating 1. The cell transfers one...

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An F+ x F- mating 1. The cell transfers one strand of DNA from its F plasmid to the F- cell via the conjugation bridge 2. The complementary strands of F plasmid DNA are synthesized 3. The recipient cell gets a complete copy of the F plasmid, and the donor cell retains a complete copy High Frequency Recombination Strains(Hfr) -can induce more than 1000x the # of genetic recombinations seen in F+ and F- -Hfr strains arise from F+ strains when the F plasmid is incorporated into the bacterial chromosome at one of several possible sites -when an Hfr cell serves as a donor in conjugation, the F plasmid initiates transfer of chromosomal DNA -only one part of the F plasmid (initiating segment) is transferred therefore the recipient cell does not become and F+ donor cell because only part of the F plasmid is transferred *-initiating segment: part of the F plasmid is transferred along with adjacent chromosomal genes Fig 8.9 The Transfer of F’ Plasmids -incorporating an F plasmid into a bacterial chromosome is reversible so, DNA incorporated into a chromosome can separate from it and again become an F plasmid -in some cases this separation occurs imprecisely, and a fragment of the chromosome is carried with the F plasmid -cells containing such plasmids are “F’ strains” (partial diploid cell (F’)) -not F+ because only a part of the F plasmid is transferred
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This note was uploaded on 02/24/2011 for the course BIO 250 taught by Professor Datt during the Spring '09 term at South Carolina.

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notes 2-23 - An F+ x F- mating 1. The cell transfers one...

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