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During a lytic cycle, the bacteriophage uses the replicative machinery of the bacterial cell to make many copies of its viral genome and to produce structural proteins of the phage tail and head. After phage DNA genomes are packaged into phage particles, the cell lyses (ruptures), releasing progeny phage capable of infecting other bacteria.

During a lysogenic cycle, the phage inserts its genome into the circular bacterial chromosome. The viral genome remains dormant in the bacterial genome, and whenever the bacterial DNA is replicated, the viral DNA insert is replicated as well. When an appropriate extracelluar signal acts on the bacterium, such as an environmental stress or ultraviolet light exposure, the viral plasmid genome is excised from the bacterial chromosome, and the phage initiates a typical lytic cycle.

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