Question

explain lysogenic cycle in virus.

Answer 1

Lytic and Lysogenic cycles are two types of viral reproduction cycle.  Lysogeny is characterized by integration of the viral nucleic acid into the genome of host. In lysogeny, circular replicon is formed in bacterial (host) cytoplasm, but bacteria continue with its normal metabolic processes and reproduction. The viral genetic material (prophage) is replicated when the bacteria undergo cell division and is transmitted to daughter cells at each subsequent cell division. Normally, the bacteria are not harmed by this process as very less amount of viral DNA is produced, and the host machinery has not been hijacked by the virus, as in the lytic cycle. Under favorable conditions, the viral DNA will undergo induction and the DNA will switch to the lytic cycle, in which the DNA is actively transcribed and translated into viral proteins. Then, the infected host cell will be full of viruses, each encapsulated in a viral capsid protein. The later events can release the viruses, causing the lysis of host cells. The released viruses then infect new host cells.

Steps in Lysogeny

Step 1: A virus infects the host cell by injecting its DNA into the host cytoplasm

Step 2: The viral DNA is read and replicated by the host machinery.

Step 3: The viral DNA is transmitted to daughter cells at each subsequent cell division.

Step 4: Induction of lytic cycle by viral DNA.

Step 5: Viruses released into environment infect new host cells.