What are chemical messengers that can travel through the bloodstream and tell cells in the body what to do.

Hormones are chemical messengers that travel throughout the body coordinating complex processes like growth, metabolism, and fertility.

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.