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Conjugation: Hfr & F' Cells quiz

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  • What does HFR stand for in HFR cells?
    HFR stands for High Frequency of Recombination, referring to cells with an F plasmid integrated into their chromosome.
  • How is an HFR cell formed from an F+ cell?
    An HFR cell is formed when the F plasmid integrates into the host chromosome of an F+ cell.
  • Is the integration of the F plasmid into the chromosome reversible?
    Yes, the F plasmid can excise itself from the chromosome, converting the HFR cell back to an F+ cell.
  • During HFR cell conjugation, what type of DNA is transferred to the recipient?
    Part of the donor cell's chromosomal DNA and a portion of the integrated F plasmid are transferred to the recipient.
  • Does the recipient cell become F+ after HFR cell conjugation?
    No, the recipient cell remains F- because it does not receive the entire F plasmid.
  • What structure is formed by HFR cells to initiate conjugation?
    HFR cells form an F pilus to bind to the F- cell and initiate conjugation.
  • What happens to the transferred DNA in the recipient cell after HFR conjugation?
    The transferred DNA may integrate into the recipient's chromosome via homologous recombination or be degraded.
  • What is the main difference between HFR and F+ cell conjugation?
    HFR cell conjugation transfers chromosomal DNA and only a portion of the F plasmid, while F+ cell conjugation transfers the entire F plasmid.
  • How are F' (F prime) cells formed?
    F' cells are formed when the F plasmid excises from the chromosome of an HFR cell, taking a fragment of chromosomal DNA with it due to error-prone excision.
  • What does the F' plasmid contain?
    The F' plasmid contains the entire F plasmid plus a small fragment of chromosomal DNA.
  • What happens during F' cell conjugation?
    The F' cell transfers the entire F' plasmid, including the excised chromosomal DNA fragment, to an F- recipient cell.
  • What is the result for the recipient cell after F' cell conjugation?
    The recipient cell becomes an F' cell, now containing the F' plasmid with the chromosomal DNA fragment.
  • How does horizontal gene transfer differ between HFR and F' cell conjugation?
    HFR conjugation transfers chromosomal DNA and a portion of the F plasmid, while F' conjugation transfers the entire F' plasmid with chromosomal DNA.
  • Why does the recipient cell remain F- after HFR conjugation?
    Because it only receives a small portion of the F plasmid, not the entire plasmid, so it cannot initiate conjugation.
  • What is the significance of error-prone excision in F' cell formation?
    Error-prone excision allows the F plasmid to take chromosomal DNA with it, creating genetic diversity in F' cells.