For bacteria that are F⁺, Hfr, F', and F⁻ perform or answer the following. Which of these cells are donors? Which is the recipient?

Key Concepts

Fertility Factor (F Factor)

The F factor is a plasmid that contains genes necessary for bacterial conjugation, allowing the transfer of genetic material between bacteria. Bacteria that possess the F factor are termed F⁺ and can act as donors during conjugation, transferring genetic material to F⁻ recipients. The F factor can exist as a free plasmid or integrate into the bacterial chromosome, leading to Hfr (high frequency of recombination) strains.

Hfr Strains

Hfr strains are bacteria in which the F factor is integrated into the chromosomal DNA. These strains can transfer chromosomal genes to F⁻ cells during conjugation, making them effective donors of genetic material. The transfer process is more complex than with F⁺ cells, as it involves the transfer of chromosomal segments rather than just the F factor itself.

F' Strains

F' strains arise when the F factor excises from the bacterial chromosome, sometimes carrying adjacent chromosomal genes with it. These strains can also act as donors, transferring both the F factor and the additional chromosomal genes to F⁻ recipients. This process can lead to genetic variation and the introduction of new traits into recipient bacteria.