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Unformatted text preview: Virus Objectives GENERAL 1. Vi rus: Genetic elements that exist in the extracellular or intracellular form. Extracellular -> virus particle/virion. Viral genome surrounded by a capsid (protein coat), sometimes surrounded by an envelope (lipid bilayer). Capsids: Protein shell that encloses nucleic acid/core/nucleoprotein complex. Composed of units -> capsomers. Capsids either helical, icosahedral, or complex. Virion: Intact, fully assembled and infective virus particle Core: An internal body found in some viruses containing nucleoprotein complex within another protein shell (i.e. capsid) 2. Initiation: (Attachment: adsorption of virus particle to host cell [random collisions] -> binding anti receptor to virus receptor [receptor involved in some normal cell function]. Entry: Enter cytoplasm [energy dependent], many mechanisms). Replication (template either is replicated for progeny, or synthesize viral mRNA -> viral protein) Assembly (all components accumulate at particular location, proteins attach to viral genome to be packed, t riggered when genome and protein exceed threshold concentration [self assembly, high affinity -> energetically favorable]. Virus release (cell lysis [usually non enveloped] or budding [enveloped usually. All budding -> virus acquire lipid envelope and modify it by inserting viral encoded proteins for attachment to host cell for next round infection, some may need...
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- Spring '10