Virus
Viruses are not cells
A virus is a very small infectious particle consisting of nucleic acid enclosed in a protein coat and, in some cases, a membranous envelope
Capsid
A capsid is the protein shell that encloses the viral genome
Capsids are built from protein subunits called capsomeres
Viral Envelopes
These viral envelopes surround the capsids of influenza viruses and many other viruses found in animals
Bacteriophage
Bacteriophages, also called phages, are viruses that infect bacteria