Question

Which one does not occur in the lytic life cycle of a virulent DNA phage?
A.The host cell lyses
B.New phages are released
C.Host cell produces a number of virions
D.Phage DNA integrates with host DNA

Answer 1

Hint: Phage or bacteriophages are viruses that are capable of infecting bacteria as well as archaea. They consist of either DNA or RNA as their genetic material.

Complete answer:
Phages cause infection by adhering to various cell surface receptors that are commonly found on the surface of bacterial cells. This is followed by injecting their genetic material inside the cell which then utilizes the host cell machinery to replicate itself . phages comprise of two different replication strategies. They are known as the lytic cycle and the lysogenic cycle. In the lytic cycle the phage DNA replicates itself followed by transcription and translation of various protein components utilizing the host machinery. These protein forms help in the formation of a large number of complete progeny phages which then leave the cell by lysing it. In a lysogenic cycle there is no lysing of the cell, instead the phage DNA integrates into the host genome and replicates along with it. They are also known as temperate phages.

Hence, the correct answer is option (D)

Note: The lytic stage is more harmful than the lysogenic one as it causes the death of the host cell. But in some cases it is seen that the phages that remain in the lysogenic stage may switch to the lytic cycle when the host cell is facing unfavorable conditions.