11 Viruses Ch10 Notes - Viruses Biol 127 Ch 10: pgs 271-298...

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Viruses Biol 127 Ch 13: pgs 389-390; Ch 16: pgs 476-478 What are viruses? - Acellular - Obligate intracellular parasites – - Generally considered to be Size of Viruses: ______________________ (Fig 10.2) - smaller than bacteria - originally referred to as Shapes of Viruses - Based on symmetry of the viral capsid: - - - Generalized Structure of Viruses - Genome is DNA or RNA - Single or double-stranded - Single piece of nucleic acid or several pieces - Capsid – protein coat - Capsomeres – subunits of the capsid - Nucleocapsid = - Envelope - some viruses have an envelope - Composed of lipids and protein - Derived from host cell’s membrane - Spikes – protein projections from the envelope or capsid - Virion = The Components of a Virus Fig 10.1 What is a Bacteriophage? Fig 10.10a Host Range and Tissue Tropism - Host range - The species (organisms) a virus can infect - Determined by what the virus can bind to - Can be narrow or broad - most viruses have a narrow host range - Examples: - This concept also applies to - Tissue tropism - The cell type(s) a virus can infect - Most viruses infect a particular cell/tissue type - Host cell must have receptor for the virus - Examples:
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Nomenclature and classification of viruses - Called by a hodge-podge of common names - Name some viruses: - How are these named? - Have been grouped based on where they replicate Pneumotropic viruses Dermotropic viruses Viserotropic viruses Neurotropic viruses - What concept does this naming refer to? - International Committee on Taxonomy of Viruses - Official way viruses are named and grouped - Established in 1966 to classify viruses - Only limited taxonomic groups are used - Viruses have common name and are grouped into genera and families (Tables 10.1 & 10.2, Appendix B) - Type and structure of genetic material - Shape - Presence/absence of envelope - Hosts they infect Genus names end in –virus Family names end in –viridae How Do Viruses Replicate? - Viruses lack functions needed to replicate themselves; They have very few genes
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This note was uploaded on 02/21/2012 for the course MICROBIOLO BI127 taught by Professor Leunk during the Spring '09 term at Grand Rapids Community College.

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11 Viruses Ch10 Notes - Viruses Biol 127 Ch 10: pgs 271-298...

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