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Essay on Bacteria and Viruses

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Bacteria are unicellular organisms called prokaryotes. Viruses are pieces of biomolecules that cannot reproduce independently. Both groups may be pathogens, or may be beneficial- sometimes, the same species or variety may be both, depending on circumstances (Starr, C., and Taggart, R., 2004.) Throughout history, pathogens and more helpful species have played vital roles in the development of humanity as a species and of the human social arrangement. Prokaryotes are divided into eubacteria and archaebacteria. Eubacteria are considered bacteria, and will be henceforth referred to as such. Archaebacteria lived in more extreme environments, are older than eubacteria, and have sufficient chemical differences to be distinct from bacteria. …show more content…

They may also metabolize chemicals in ways that are good, such as the ways that make cheese and yogurt, or clean up oil spills. They may also be commensals, such as Escherichia coli.
The positive effects of viruses are less obvious. Viruses can function as vaccines for similar but more harmful diseases, be scientifically interesting and broaden our understanding of biology, or have applications in genetic engineering as transfer vectors (“Gene transfer vector”, 1999.) This is because of the way that viruses infect cells and replicate. Viruses consist of a protein coat around a nucleic acid, which may be DNA or RNA- not a combination of the two. The protein coat functions to protect the nucleic acid and attach to and recognize a host cell. Shapes of viruses are helical, polyhedral, enveloped, and complex (Starr, C., et al, 2004). Enveloped viruses are an exception to the protein coat structure, in that they have a lipid bilayer surrounding. Viruses are 20 to 400 nanometers in diameter (Elert, G., 2004). Independent of a host cell, a virus is called a virion. When just the nucleic acid is present, it is called a viroid.
Viruses can infect cells, including human cells, in two ways. Both start out similarly: a virus particle attaches to a cell and injects nucleic acid. From there, the nucleic acid can stay in the cytoplasm, where it uses ribosomes to replicate itself. Eventually, the cell lyses, releasing from 100 to 200 new copies of the

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