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Transfer of the F factor

Transfer of the F factor. Transfer of the Hfr F+ factor. Excision of the F+ factor also occurs spontaneously at low frequency . Begin with Hfr cell containing F+ . Small section of host chromosome also may be excised, creating an F’ plasmid.

Samuel
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Transfer of the F factor

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  1. Transfer of the F factor

  2. Transfer of the HfrF+ factor

  3. Excision of the F+ factor also occurs spontaneously at low frequency. Begin with Hfr cell containing F+. Small section of host chromosome also may be excised, creating an F’ plasmid. F’ plasmid is named for the gene it carries, e.g., F’ (lac)

  4. Interrupted mating experiment

  5. F plasmid F- bacteria F plasmid 2 Conjugation F+ bacteria Mating Bridge

  6. F plasmid F+ bacteria F- bacteria F plasmid 2 Conjugation Mating Bridge

  7. Genetic map-results of interrupted E. coli mating experiment

  8. F+ factor (fertility factor)- a sophisticated plasmid OriT, Origin of transfer insertion sequences, genes for own replication, genes for own transfer

  9. Conjugation converts an F- to F+. Original F+ remains F+ Note: No host genes (in blue) transferred from F+ to F-

  10. To transfer host genes, need an Hfr strain (high frequency) Homologous Recombination here One cell will have one or another of these F+ to Hfr relative low frequency (~few %). X-ray induces Hfrs. Why?,

  11. Using an Hfr for gene transfer

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