Viruses

Why are Viruses considered an exception to the Cell Theory? Viruses are prolific. They have been found in almost all parts of the Earth, including the Arctic. They infect nearly every form of life from the simplest unicellular organism (bacteria) to complex mammals, such as humans. The structures of all human viruses have several common attributes. First is their incredibly small scale. There are 10 x10+9 nanometers in a meter. Viruses are so minuscule that they …

…the host genome. At a later date, the viral genome may be activated and can enter a lytic state. But most of the time, the viral genome just stays silent in the host cell. In latency, a form of lysogeny, the viral genome stays in the host cell, but is not necessarily incorporated. The genome is present but does not produce many products. Again, the viral genome can be reactivated, generating disease in the host.