Final answer:
The targeting function of host cells in the viral cycle is to provide a specific receptor site for the virus to attach and enter the cell. Once inside, the virus uses the cell's machinery to replicate and produce new virions. The host cell is then either destroyed or the virions are released without killing the cell.
Step-by-step explanation:
In the viral replication cycle, host cells play an important role by providing the necessary resources for the virus to replicate. One of the targeting functions of host cells is to provide a specific receptor site on the cell membrane that the virus can attach to. This interaction between the viral attachment proteins or glycoproteins and the specific receptor is crucial for the virus to enter the host cell and initiate the replication process.
Once inside the host cell, the virus uses the cell's machinery and metabolism to copy its genome and manufacture its own proteins. The viral replication cycle can cause structural and biochemical changes in the host cell, leading to cytopathic effects that can damage or destroy the cell.
The last step of the viral cycle is the release of the newly formed virions from the host cell. Some virions are released when the host cell dies, while others bud through the cell membrane without killing the cell.