Final answer:
The outer covering of a virus is called the capsid, which is made up of protein subunits called capsomeres. Some viruses also have an outer structure called a viral envelope, which is made from portions of the host cell membranes.
Step-by-step explanation:
All viruses have a nucleic acid genome covered by a protective layer of protein called a capsid. The capsid is made up of protein subunits called capsomeres. Some viral capsids are simple polyhedral spheres while others are quite complex in structure. Additionally, some viruses have an outer structure called a viral envelope, which is made from portions of the host cell membranes.