This paper, below, was a project for my Virology class. I really wanted to go into more detail, but she specifically asked for around one page and I found, if I tried to talk about any other aspect of this debate, that I ran well over that limit. So am I overall happy with the paper? Well, no, not really. Do I think it's reasonable for being limited to a page? You bet'cha. Let me know what you think!
Oh, the prompt was simply, "Are Viruses Alive?" We had to take a side, though I'd like to place them pretty firmly in the "kinda sorta" category.
Characterizing viruses as alive or nonliving presents a very real challenge in modern biology; one must, before taking a stance, come with a functional definition of life that can clearly delineate living from the near-living. This presents a problem, as we don’t really have a definition that accomplishes this. We know to some extent how life functions, but have difficulty coming up with a clear, concise definition that excludes all things dead yet includes all living things. The task would be easy if not for the strong societal connotation that “alive” bears. You can see it permeated throughout our culture. The 1980s movie Short Circuit focused heavily on this idea, featuring a robot that had argued for his own sentience with such clever catchphrases as “Number Five is alive!” Humans are overly concerned with the notion of “living” when we actually tend to mean “sentient” or “self-aware.” Rare is the person who cares if we kill a colony of bacteria, but human life or, to some, animal life bears greater significance. This concern for the existence of sentient, feeling organisms seems to charge “life” and its variants with a connotation that can impede our efforts to define it.
We commonly consider an organism “alive” if it has a metabolism, responds chemically to its environment, maintains a separation from itself and its environment, and is capable of reproduction. This definition carries with it many problems, as no single characteristic is exclusive to life, and some may, in fact, exclude forms of life. A man who is infertile is not capable of reproducing more copies of himself (save at a cellular level), but is still considered alive. A house has clear boundaries, but is quite dead. A car has a form of metabolism, and nearly everything can respond chemically to their environment in some fashion or another. A better definition of life must be more specific to have any relevance to biology.
We know a few things about what we define as life. All clearly categorized living things have a genome, a code of instructions that can be replicated by the organism. This genome also undergoes a process to create proteins based on that genome (traditionally transcription followed by translation), which can be used for a variety of purposes. These features function elegantly, but their function seems little more than that of a machine. The genome is the programming code, the proteins created by that code are the gears (enzymes and cell signaling proteins), and while capable of some self-repair there comes a point when the machine is no longer capable of functioning. In machines we might call it simply “irreparably damaged” or “junk.” In life we call it “dead.” A “living” machine must be organic and utilize a genome, certainly, but that makes it a category of machinery, not a classification separate from it. Viruses are merely simpler organic machines. They are capable of a set of processes defined by their genomic code, and have a point where they can no longer function. By this presented argument, viruses are alive. A bacterial spore has little to no function, but is still considered alive since it can be viable years after encysting. If we accept these simple spores as alive, then a virus, which may like smallpox remain dormant for years and still be virulent, should be considered alive. A prion, carrying no genetic code but being a peculiar infective result of that code, would not be considered alive. It is a rogue cog in the machinery of life, causing significant damage yet holding no heritable, reproducible advantage or capability.