Viruses, Bacteria, and Prions

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Viruses, bacteria, and prions can be rather similar. For example, their ability to affect a cell’s reproduction cycle, or their negative results for the structures they affect. On the other hand, bacteria can actually be beneficial to the structures they infect. Another difference is that bacteria reproduce without assistance. These three infectious devils are extremely unique but vaguely familiar at the same time. In a virus, the structure contains a capsid, an envelope, and a nucleic acid. The capsid is a protein shell that encases the nucleic acid. This shell is made of protein subunits called capsomers. The capsid has three functions; one is to protect the nucleic acid from digestion by the enzymes. Another is that it has special sites on its surface that allows the virion to attach to the host cell. The third function is that it provides proteins for the virion to penetrate the host cell membrane. The virus ‘glycoprotein envelope, surrounds the nucleocapsid. The envelope has two lipid layers with protein molecules interspersed. They may also contain material from the membrane of the host cell as well as its own. Some may also develop spikes on the envelope to help attach to cell surfaces. The final part of a virus, nucleic acid, encodes the genetic information for the synthesis of proteins. Most viruses maintain genetic information with RNA rather than DNA. There are only two types of RNA based viruses, plus strands that go through translation, and negative strands that go through transcription. Viruses are shaped as rods, filaments, or spheres. Viruses are known to infect both plants and animals. Viruses reproduce through the lytic and lysogenic cycles. The lytic cycle starts with the virus attaching to a host cell. The h... ... middle of paper ... ... 2014. Web. 19 Apr. 2014. . "Reproduction of Viruses." McGraw-Hill Education. McGraw-Hill Education, 1 Jan. 2014. Web. 19 Apr. 2014. . Carter, J. "Bacterial Diseases." Bacterial Diseases. N.p., 16 Jan. 2014. Web. 19 Apr. 2014. . "Prion Diseases." John Hopkins Medicine. John Hopkins University, 1 Jan. 2014. Web. 19 Apr. 2014. <http://www.hopkinsmedicine.org/healthlibrary/conditions/nervous_system_disorders/prion_diseases_134,56/>. Tritz, Gerald. "Educational Objectives." Prions & Viroids. Kirksville College of Osteopathic Medicine, 1 Jan. 2000. Web. 19 Apr. 2014. .

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