The correct answer that describes a characteristic of the lysogenic cycle is:
d. Viral DNA is inserted into host DNA, and is replicated when the cell divides.
Explanation:
What is a Virus? A virus is a microscopic infectious agent that can only replicate inside the living cells of an organism. Viruses consist of genetic material (either DNA or RNA) encased in a protein coat (capsid) and, in some cases, an additional lipid envelope. They lack the cellular machinery necessary for metabolism and reproduction and depend on host cells to reproduce and propagate.
How do Viruses Spread? Viruses spread primarily through various routes, including:
- Direct contact: Touching an infected person or surface, leading to transmission.
- Respiratory droplets: Coughing, sneezing, or talking can expel droplets containing viruses, which is inhaled by others.
- Vectors: Some viruses spread through vectors like mosquitoes (e.g., dengue, Zika virus).
- Contaminated food or water: Certain viruses can be transmitted through ingestion.
- Sexual contact: Some viruses, like HIV and HSV, spread through sexual contact.
How do Viruses Make Us Sick? Viruses can make us sick by:
- Infecting host cells: Once inside the body, viruses attach to and enter host cells, utilizing cellular machinery to replicate. This can disrupt normal cell function.
- Triggering immune responses: The presence of viruses can stimulate the immune system, leading to inflammation and associated symptoms such as fever, fatigue, and pain.
- Cell death: In some cases, the replication of a virus can cause cell death either directly (by causing lysis of cells) or indirectly through the immune response, resulting in tissue damage.
In the context of the lysogenic cycle, the viral DNA is integrated into the host's genome, allowing the virus to replicate along with the host cell's DNA during cell division without immediately harming the host cell.