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Appendix B. Microbial Life Forms > Viruses Are Inert Until They Infect

Viruses Are Inert Until They Infect

In molecular terms, viruses are much simpler than cellular pathogens and parasites. They are composed of a nucleic acid, either RNA or DNA, a protein coat that protects the nucleic acid, and often several other proteins that form an outer envelope. Some viruses also carry important enzymes with them. The protein coat of viruses can be simple, or it can comprise many proteins that form the complex head and tail structures seen with some bacteriophages (viruses that attack bacteria). Other viruses, such as human immunodeficiency virus (HIV), acquire an outer coat of membrane when they exit human cells (release of virus occurs by the infected cells forming small buds that pinch off, releasing membrane-coated virus). We stress that no virus ma....


  

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