Describe the structure of viruses.

(N/A) Viruses are non-cellular organisms characterized by having an inert crystalline structure outside the living cell.
They are obligate parasites.
In addition to proteins,viruses also contain genetic material that could be either $RNA$ or $DNA$.
No virus contains both $RNA$ and $DNA$.
$A$ virus is a nucleoprotein,and the genetic material is infectious.
In general,viruses that infect plants have single-stranded $RNA$,and viruses that infect animals have either single or double-stranded $RNA$ or double-stranded $DNA$.
Bacterial viruses or bacteriophages (viruses that infect the bacteria) are usually double-stranded $DNA$ viruses.
The protein coat called capsid made of small subunits called capsomeres,protects the nucleic acid. These capsomeres are arranged in helical or polyhedral geometric forms.