Virions of some of the most common human viruses with their relative size. The nucleic acids are not to scale.
Diagram of how a virus capsid can be constructed using multiple copies of just two protein molecules
Structure of icosahedral adenovirus. Electron micrograph with an illustration to show shape
Bacteriophage Escherichia virus MS2 capsid. This spherical virus also has icosahedral symmetry.

The genetic material within virus particles, and the method by which the material is replicated, varies considerably between different types of viruses.

Transmission electron micrograph of multiple bacteriophages attached to a bacterial cell wall