MICR 2420 Study Guide - Final Guide: Intracellular Parasite, Icosahedral Symmetry, Tobacco Mosaic Virus
2 Dec 2018
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Document Summary
Viruses: describe the various types of viral particle symmetry. Viruses are considered obligate intracellular parasites since they can only be maintained in living cells. Obligate means that it must be done in that manner. Viruses must carry out their reproduction by parasitizing a host cell. The most important criteria: nature of genome-including nature, shape, strandedness and whether it is segmented, capsid symmetry, envelope or no envelope, size of viral particle, host range. Their capsids have elongated 20 side heads that enclose their dna. Attached to the head is a protein tail piece with tail fibers that phages use to attach to a bacterium. Some viruses, for example hiv, are converted between rna and dna during infection. Hiv has a single-stranded rna chromosome that is converted to a double-stranded dna molecule upon infection and this double-stranded dna molecule then gets inserted into the hosts chromosome from which location viral replication and reproduction are directed.
