The topic of viruses has become quite prevalent in today’s time and this brings the question in whether or not they are alive. For and organism to be classified as living, a set of criteria must be fulfilled: response to their environment, growth and evolution, reproduction, metabolism, maintain homeostasis, be composed of cells and to pass genetic traits to offspring.
Viruses satisfy some, but not all of the criteria of living things. Viruses are not composed of cells, and cannot reproduce without the use of a host. After a virus infects an organism, it is able to duplicate by inserting its DNA into the hosts cells which then reproduce the new virus DNA as well. One of the criteria of livings things is the ability to use oxygen and sugar and form energy. Viruses are also not capable of this as they do not consume energy. Since viruses do not have any regulatory organelles, they are not able to maintain homeostasis as they lack the ability to monitor or adjust their internal state.
Although viruses do not contain all criteria of life, they are still able to react to their environment as they enter organisms and find certain cells to infect. Viruses can also evolve as the genetic copies created may contain errors which may change the viruses’ characteristics. Errors which increase the fitness of the virus will result in the new strain to infect more cells, becoming a more dominant strain. The criteria of life are an important way of distinguishing whether or not organisms are alive or not. Although the argument of viruses is an interesting one, they still do not satisfy all the criteria therefore placing them in the category of “not alive”.
Applied Plant Ecology Winter 2020 