Transduction is the process whereby DNA is
transferred between bacteria by packaging into a phage particle. Transduction
begins when a phage that has infected a bacterium mistakenly packages a segment
of the host cell’s chromosome into its capsid, or
head, instead of its own DNA. The bacteriophage
shown injects its DNA into a cell, where it is used to produce numerous new
phage particles. Note that the front-most progeny phage being assembled in
this cell internalizes a piece of the host’s DNA, shown as a white wavy line.
When the cell lyses and releases the mature phage particles, the phage
containing a portion of the bacterial chromosome proceeds to infect a new
cell. This phage is called a transducing phage
since it can transfer the genetic material of the first bacterium into the
second. However, since no phage DNA enters the target cell, the bacterium
does not produce phage or lyse. Instead, the infecting DNA may undergo a
homologous recombination event with the bacterial chromosome, as shown. A
single strand from each helix invades the other DNA molecule, resulting in
phage-mediated transfer of genetic material from one bacterium to the other.
This completes the general process of transduction.
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