Bacterial Genetics: Transduction and Conjugation

Vocabulary flashcards covering bacteriophage lifecycles, generalized versus specialized transduction, and plasmid-mediated bacterial conjugation.

Bacteriophage (Phage)

A virus that infects bacteria and can serve as a conduit for horizontal gene transfer.

Att site (Attachment site)

A very specific location in the bacterial host chromosome where a temperate phage incorporates its DNA during the lysogenic cycle.

Temperate bacteriophage

A type of phage capable of undergoing a lysogenic life cycle by incorporating its DNA into the host chromosome; it is the only type of phage that can mediate specialized transduction.

Prophage

Phage DNA that has integrated into the bacterial host chromosome and replicates along with the host cell during each cell division.

Induction

The process in which a prophage excises itself from the host chromosome and enters the lytic cycle to produce virus particles.

Generalized transduction

A low-efficiency gene transfer process initiated during the lytic cycle of virulent phages in which random fragments of degraded bacterial host DNA are mistakenly packaged into phage coats.

Transducing particle (Transducing phage)

A defective phage particle containing host bacterial DNA instead of viral DNA, which delivers donor genetic material into a recipient bacterium rather than causing a productive viral infection.

Specialized transduction

A highly efficient gene transfer process initiated during the lysogenic cycle of temperate bacteriophages, in which specific bacterial chromosomal genes adjacent to the integration site are excised along with phage DNA.

Recombinant cell

A recipient bacterium that has received DNA from a donor bacterium and incorporated that foreign DNA into its own chromosome through recombination.

Conjugation

A mechanism of horizontal gene transfer—sometimes referred to as mating or bacterial sex—mediated by direct cell-to-cell contact.

F factor (Fertility factor / F plasmid)

A plasmid found in certain E. coli cells that encodes proteins necessary to facilitate its own transfer, including the synthesis of conjugation pili.

Conjugation pili (Sex pili)

Proteinaceous, rod-like structures produced by an $F^+$ cell that extend to an $F^-$ cell and pull the two cells together to facilitate plasmid transfer.

$F^+$ cell

A bacterial donor cell that contains an F factor and transfers a single-stranded copy of the plasmid to a recipient cell during conjugation.

$F^-$ cell

A bacterial recipient cell lacking the F plasmid that receives a single-stranded copy of the F factor during conjugation, converting it into an $F^+$ cell.