Viruses

Viruses are non-cellular microscopic organisms, which are composed of genetic material and protein that can invade living cells. They belong to the family viridae and genus virus.

Characteristics of Viruses

• They have no cell nucleus.
• They do not have an organized cell structure.
• They typically have one or two strands of DNA or RNA.
• They are enclosed in a protective coat of protein called the capsid.
• They do not respire, do not metabolize and do not grow but they do reproduce.
• They are considered both as living and nonliving things, as they are inactive outside the host cell, and are active when present inside host cell.