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Chapter Overview |
Chapter 29: Viruses |
We have examined the nature and classification of organisms. In this chapter, we examine the nature and classification of a non-organism lacking the criteria for an organism. Viruses cannot reproduce themselves. Despite this flaw, they are reproduced and spread over the world. Viruses are the "Huckleberry Finn" of the biological world--getting organisms to do the viruses' work of reproducing genome and container. The AIDS virus is so efficient in dealing with our immune system that it would appear to have been educated in a biology course.
The diversity of viruses is remarkable! A virus is basically a nucleic acid contained in a protein shell called a capsid, and less frequently surrounded by a fatty capsule. The phage virus that preys upon bacteria is still more complex. Geometrically, viruses tend to be helical or isometric. Whatever their shape or composition, there is a commonality. They all gain entry into a living cell and induce it to replicate their genomes and manufacture containers for the genomes. The viruses then may thanklessly destroy their benefactor cell upon exiting. The list of diseases caused by viruses is long and frightening. It is highly improbable that anyone reading this book has entirely avoided viral diseases or will in the future. As of this writing, it is a fair generalization that our technology has failed to produce a cure for viral diseases--but it will. An irony in which one might derive some satisfaction is that viruses will help us, as a result of genetic engineering, develop a cure for viral diseases and to make many other contributions to the science of medicine.
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