Viri come in many shapes, but are of very similar structure to the HIV virus illustrated. All have a form of the Docking Glycoprotein with which to penetrate Eukaryote, Archaea and Bacteria cells, as they cannot reproduce except by using facilities within those cells. Because they cannot reproduce by themselves, they are called "organisms on the edge of life" rather than life forms. To reproduce, they subvert the DNA of a penetrated cell to use its Ribosomes to generate copies of themselves. Illustration by NIAID distributed under license Creative Commons Attribution v2.0 Generic.
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