What is the function of a capsid in a virus?

The function of a capsid in a virus is to protect the viral genetic material and aid in the process of entering host cells. The capsid is the protein shell that encases and safeguards the viral genome, which can be either DNA or RNA. This protective structure is critical because it shields the genetic material from degradation by enzymes and the external environment.

When a virus infects a host cell, the capsid plays a vital role in mediating the interaction with the host's cellular machinery. It often contains specific proteins that recognize and bind to receptors on the surface of the host cell, which facilitates the entry of the virus into the cell. Once inside, the viral genome can then hijack the host’s cellular processes to replicate and produce new viral particles.

This function of the capsid is essential for the virus's ability to propagate and infect additional cells, making it a key component of viral structure and functionality.