Question

difference between the lytic and lysogenic cycle

Answer 1

The lytic and lysogenic cycles are two different methods by which bacteriophages (viruses that infect bacteria) can replicate and propagate within a host bacterial cell. Here are the key differences between the two cycles:

### Lytic Cycle:
1. **Definition**: The lytic cycle is a viral reproductive process in which the virus immediately takes over the host cell's machinery to produce new viral particles, leading to the destruction (lysis) of the host cell.
2. **Stages**:
- **Attachment**: The virus attaches to the surface of the bacterial cell.
- **Penetration**: The viral DNA or RNA is injected into the host cell.
- **Replication**: The host cell's machinery is used to replicate the viral genetic material and produce viral proteins.
- **Assembly**: New viral particles are assembled from the newly made viral components.
- **Release**: The host cell is lysed (burst) releasing the newly formed viruses to infect other cells.
3. **Outcome for Host Cell**: The host cell is destroyed in the process, usually dying shortly after the virus is released.

### Lysogenic Cycle:
1. **Definition**: The lysogenic cycle is a viral reproductive process where the viral DNA integrates into the host cell's genome and replicates along with it. The virus can remain dormant for long periods.
2. **Stages**:
- **Attachment**: The virus attaches to the bacterial cell.
- **Penetration**: The viral DNA is injected into the host.
- **Integration**: The viral DNA integrates into the bacterial chromosome, becoming a prophage.
- **Replication**: When the host cell divides, the viral DNA is replicated along with the bacterial DNA, allowing the virus to be passed to daughter cells.
- **Induction**: Under certain conditions (like stress), the prophage can be excised from the bacterial genome and enter the lytic cycle.
3. **Outcome for Host Cell**: The host cell can survive and replicate for many generations with the prophage incorporated in its genome without immediate lysis. However, the virus can switch to the lytic cycle later.

### Summary:
- **Lytic Cycle**: Rapid replication, destruction of host, results in cell lysis.
- **Lysogenic Cycle**: Incorporation of viral DNA into host genome, no immediate destruction, can be triggered to enter lytic cycle later.

These cycles highlight the different strategies viruses can use for propagation, survival, and adaptation in bacterial hosts.