Lytic cycle: The bacteriophage replicates only inside the bacterial cell. The first step is the attachment of bacteriophage to host cell at receptor site on the bacterial cell wall. During this week chemical union between vision and receptor sites takes place. Second step is penetration in which the tail releases the enzyme lysozyme to digest a portion of the bacterial cell wall. The tail sheath contracts and tail core is forced into the cell through cell wall and cell membrane. The virus injects its DNA into the bacterial cell just as the syringe is used to inject the vaccine. The protein coat remains outside the cell. Many animal viruses, however enter the host cell intact i.e., the entire virus penetrates the host cell by endocytosis.Immediately after entering the host cell, the viral DNA takes the control of the host's biosynthetic machinery and induces the host cell to synthesize necessary viral components (DNA, proteins0, and starts multiplying about 25 minutes. After initial infection, Approximately 200 new bacteriophages are formed with in the host cell. Now bacterial cell burst, i.e., it undergoes lysis. Newly formed phages are released to infect other bacteria and start another lytic cycle. The phage, which causes lysis of the host cell, is known as lytic or virulent phage.
