Genetic Analysis using Hfr and F′ Strains of E. coli

  • P. F. Smith-Keary
Part of the Macmillan Molecular Biology Series book series


When F+ and F cells are mixed they rapidly form mating pairs and copies of F are transferred from the F+ to the F cells, converting all the latter to F+. In these crosses not only is F transferred at very high frequency but also segments of the F+ donor chromosome are transferred at very low frequency (10−6 to 10−7) forming cells that are partial diploids or merozygotes; this transfer can be followed by recombination between the segment transferred from the F+ and the corresponding region of the F chromosome to produce rare genetic recombinants. Some researchers believe that the occasional chromosome transfer observed in F+ × F crosses is due to rare Hfr cells arising spontaneously in the F+ population; however, since most of the recombinants are F+ and not F (as they are in Hfr × F crosses) it seems unlikely that this is the only explanation.


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References and related reading

  1. Jacob, F. and Wollman, E. L., Sexuality and the Genetics of Bacteria, Academic Press, New York (1961).Google Scholar
  2. Low, K. B., ‘Escherichia coli K-12 F-prime factors, old and new’, Biol. Rev., 36, 587 (1972).Google Scholar
  3. Wollman, E.L., Jacob, F. and Hayes, W., ‘Conjugation and genetic recombination in Escherichia coli K-12’, Cold Spring Harbor Symp. Quant. Biol., 21, 141 (1956).CrossRefGoogle Scholar

Copyright information

© P. F. Smith-Keary 1988

Authors and Affiliations

  • P. F. Smith-Keary
    • 1
  1. 1.Trinity CollegeDublinIreland

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