For years, scientists debated whether or not viruses are living organisms. The most confusing thing about viruses is that they display characteristics of both living and nonliving beings (Lourerio, 2006). Even after years of research and argument, we have not come to a final conclusion to this mind boggling question: Are viruses alive?
Viruses are miniscule parasites that spread infection through all species of living things, plants and animals. Parasites are completely dependent on other living organisms (Miller & Levine, 2008). A virus is made up of a DNA or an RNA molecule, a protein outer coating, known as a capsid, that gives the virus protection and the ability to transfer it’s genetic material into cells (Lourerio, 2006). Viruses are insanely small, about a thousand times smaller than bacteria (Apex Learning, 2007). They spread by reproducing, but in a very unique way. The capsid has pointy contraptions that allow the virus to attack a host cell. A host cell can be any cell, plant or animal. After the virus has attached to the cell, it releases its DNA or RNA into the host cell (Apex Learning, 2007). The virus’s genetic material forces the host cell into creating more viruses. The host cell can only hold so many viruses, so once the cell creates too many, the cell will burst and release all of the created viruses to attack new cells and to spread the virus (Apex Learning, 2007). Over time, viruses mutate many times and they are continuously evolving (Miller & Levine, 2008).
Before determining whether or not a virus is alive, the criteria for living must be established. First and foremost, living things are made up of cells, the building blocks of life according to the cell theory (Loureiro, 2006). Living things must also be able to replicate or reproduce (Villarreal, 2004). Other criteria that living things must meet are the ability use energy, grow and develop, and respond and adapt to the surrounding environment (Apex Learning, 2007). Other things that define life are its ability for metabolic functions and “[Life] require[s] a critical level of complexity” (Villarreal, 2004, 3). It must be made clear that even non living things can have some of these traits, but that doesn’t mean they are living (Apex Learning, 2007).
Examining a virus’s existence and what it means to be alive, I have come to the conclusion that viruses are not living beings. Most importantly, viruses are not made of any cells. Without the basics of life, how can you have life? Also, according to Whitehead Institute for Biomedical Research, “The simplest life forms are unicellular organisms” (Lourerio, 2006, 1) while according to the Biology textbook, “viruses are smaller and simpler than the smallest cells”. (Miller & Levine, 2008, 483). If a virus is indeed simpler than the simplest form of life (unicellular organisms i.e. bacteria), then it is not a form of life.
Some scientists believe that because of the extraordinary processes that happen inside of an infected host cell, viruses are alive (Apex Learning, 2007). It is true that viruses can reproduce and mutate (adapt to the environment) while the genetic material is residing in a host cell, but without a cell to infect and produce more viruses, the virus themselves do nothing. Some scientists also believe that because virus parts are made and put together in the host cell, that is a form of growth, another criteria for life (Apex Learning, 2007). Once again, that is only something that can be done in the host cell. Outside of the host cell, the virus simply exists. It has no activity within the capsid, therefore it is not growing, metabolising, reproducing, or mutating on its own. (Apex 2007)
In conclusion, viruses are capable of so much yet so little. They cannot exist to the extent that they do without the aid of a host cell. Viruses themselves are completely incapable of making any environmental growth, expansion, and impact. When a being is utterly dependent on a living organism to actually live, it is not living.
1.Beyond Books, Apex Learning Inc. Are Viruses Alive?. 2007.
2.Lourerio, Joana. Ask a Scientist Archives. Whitehead Institute for Biomedical Research. MIT. 2006
3.Miller, K. R., & Levine, J. S. (2008). Viruses and Living Things. Prentice Hall biology (pp. 482-483). Upper Saddle River, N.J.: Pearson/Prentice Hall.
4.Villarreal, Luis P. "Are Viruses Alive?" Are Viruses Alive?. Scientific America. December 2004.