Identify the steps of the lysogenic cycle.
provirus formation
replication and assembly of virus
attachment and entry
provirus leaves
lysis and release of virus
cell division
The Correct Answer and Explanation is :
The lysogenic cycle is a method of viral reproduction that involves the integration of viral DNA into the host cell’s genome. This cycle contrasts with the lytic cycle, where the virus immediately replicates and destroys the host cell. The steps of the lysogenic cycle are as follows:
- Attachment and Entry: The virus attaches to the surface of the host cell using specific receptor sites. Once attached, the viral genetic material is injected into the host cell.
- Provirus Formation: Instead of immediately taking control of the host’s cellular machinery, the viral DNA integrates into the host’s genome, becoming a provirus. This integration allows the viral DNA to be replicated alongside the host cell’s DNA during cell division.
- Cell Division: The host cell, now containing the provirus, undergoes mitosis, replicating its entire genome, which includes the viral DNA. As the host cell divides, each daughter cell carries the proviral DNA, thus propagating the virus without causing immediate harm.
- Replication and Assembly of Virus: Under certain conditions, such as environmental stress, the provirus can exit the host genome and initiate the lytic cycle. The viral DNA is transcribed and translated, leading to the production of viral proteins and the replication of the viral genome.
- Provirus Leaves: The newly assembled viruses can exit the host cell through processes such as budding or lysis, depending on the virus type. If the virus buds off, the host cell may survive; however, if the virus lyses the cell, the host cell is destroyed.
- Lysis and Release of Virus: In the lytic phase, the host cell undergoes lysis, releasing new viral particles into the environment, where they can infect other cells, continuing the viral life cycle.
In summary, the lysogenic cycle allows viruses to remain dormant within a host cell, replicating along with the host’s DNA, which can lead to future viral outbreaks under specific conditions. This cycle is significant in viral pathology, especially for certain bacteriophages and human viruses like HIV.