Are viruses living?

What is a virus?

• Ultramicroscopic entity that can be found everywhere.

• Consists of nucleic acid wrapped in protein capsid

• Can be pathogenic or non-pathogenic.(1% of viruses are pathogenic)

• Survive off a living host cell

Qualifications of Living Organism

x= Needs a host cell to perform these functions

XxxxxXVirus

XXXXXXOrganism

EvolutionMetabolismHomeostasisGrowthReproductionResponds to Stimuli

Living Organism vs. Virus

Special Circumstances

• Stages of life (Dormant vs. Active)

• Certain viruses (Giant virus)– Mimivirus considered missing link

– Discovered in 1992 by a French scientist– Different from a virus in shape and size

Comparison to parasite

• Both have the need for a host cell

• Reproduction and metabolism are determined by host

• Parasites can self replicate while viruses need host

Questions?

Sources

• Princeton University, wordnetweb.princeton.edu, October 29 2009.• Farlex, medical-dictionary.thefreedictionary.com, 2009• Science Daily, New Study on Mimi Virus, Chuan Xaio, April 29 2009