Download Transduction - Lytic and Lysogenic Infections • In a lytic infection the

Partial Diploid Formation (continued)
Transduction - Lytic and Lysogenic Infections
Lytic Infection
Lysogenic Infection
integration
excision
x
excision
integration
prophage
• In a lytic infection the bacteriophage
binds to the surface of the bacterial
cell and injects its DNA. The DNA is
replicated and expressed using host
cell systems. The DNA and viral
proteins assemble into new virus
particles. The host cell lyses and the
new virus particles are released.
• A bacteriophage that can only
undergo a lytic infection is said to be
virulent.
Genetics Handout 27.1
• In a lysogenic infection the
bacteriophage binds to the surface of
the bacterial cell and injects its DNA.
The DNA integrates into the host cell
chromosome forming a prophage. The
prophage is replicated with the host
cell DNA. In some cells the prophage
excises and produces a lytic infection.
• A bacteriophage that can undergo a
lytic or lysogenic infection is said to
be temperate.
Transduction - Generalized
• Virus incorporates random fragment
of host cell DNA during assembly.
x
• On infection fragment is transferred
into cell.
• DNA fragment can recombine with
the bacterial chromosome.
x
• Any gene can be transferred.
• Mapping is possible. Loci that are
close together can be transduced
together. Loci that are far apart will
not fit into virus particle.
Transduction - Specialized
• Virus incorporates adjacent fragment
of host cell DNA during excision.
x
x
• On infection fragment is transferred
into cell.
• DNA fragment can recombine with
the bacterial chromosome.
• Only genes flanking the prophage can
be transferred.
Genetics Handout 27.2