5. Genetics of Bacteria and Viruses

For bacteria that are F⁺, Hfr, F', and F⁻ perform or answer the following.

Which of these cells are donors? Which is the recipient?

For bacteria that are F⁺, Hfr, F', and F⁻ perform or answer the following.

Describe the state of the F factor.

How do we know whether or not genetic recombination between bacteria involves cell-to-cell contact?

The flow diagram identifies relationships between bacterial strains in various F factor states. For each of the four arrows in the diagram, provide a description of the events involved in the transition.

Conjugation between an Hfr cell and an F⁻ cell does not usually result in conversion of exconjugants to the donor state. Occasionally, however, the result of this conjugation is two Hfr cells. Explain how this occurs.

With respect to F⁺ and F⁻ bacterial matings, answer the following questions: What is the genetic basis for a bacterium's being F⁺.

With respect to F⁺ and F⁻ bacterial matings, answer the following questions: How was it established that chromosome transfer was unidirectional?

With respect to F⁺ and F⁻ bacterial matings, answer the following questions: How was it established that physical contact between cells was necessary?

List all major differences between:

(a) The F⁺ x F⁻ and the Hfr x F⁻ bacterial crosses

(b) The F⁺, F⁻, Hfr, and F' bacteria.

Explain the importance of the following features in conjugating donor bacteria:

pilin protein

Explain the importance of the following features in conjugating donor bacteria:

the origin of transfer

Explain the importance of the following features in conjugating donor bacteria:

T strand DNA

Explain the importance of the following features in conjugating donor bacteria:

relaxase

Explain the importance of the following features in conjugating donor bacteria:

the relaxosome

Explain the importance of the following features in conjugating donor bacteria:

homologous recombination