Viruses: 1

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Viruses: 1
2012-11-26 20:43:10
Bio Final

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  1. Virus definition
    a.      Viruses are smaller and simpler and lack structures and metabolic machinery found in a cell; it is an infectious particle consisting of little more than genes packaged in a protein coat
  2. Are they living or nonliving?
    •                                                               i.      Researchers thought they were the simplest of living forms
    •                                                             ii.      However, they can’t reproduce or carry out metabolic activities outside of a host cell= not alive
    • 1.      “lead a kind of borrowed life” 
  3. a.      Viruses have unique genetic mechanisms that help understand and develop techniques that enable __of genes
  4. a.      Viruses detected indirectly
                                                                  i.      __
    1.      Stunts growth of tobacco plants and leaves their leaves a mosaic of colors
    Tobacco mosaic disease
  5. Adolf Mayer
    •                                                                                                                                       i.      Discovered he could transmit the disease from plant to plant by rubbing diseased sap onto healthy plants
    • 1.      Assumed it was bacteria
  6. Dimitri Ivanowsky
                                                                                                                                          i.      Tested hypothesis of it being bacteria by passing sap through filter to remove bacteriaà disease still resulted; still convinced that it was bacteria
  7. a.      Martinus Beijerink 
    •                                                                                                                                       i.      Carried out experiment showing that infectious agent in filtered sap could replicate
    • 1.      Pathogen replicated only within the host infected
    • a.      Mysterious agent could not be cultivated
    •                                                                                                                                     ii.      Credited with being the first scientist to detect viruses
  8. Wendell Stanley
    confirmed his suspicion when he crystallized the tobacco mosaic virus (TMV)
  9. a.      Structure
                                                                  i.      Tiniest: __nm
                                                                ii.      __particle consisting of __ enclosed in a __ and, for some viruses, surrounded by a __
    • 20
    • Infectious
    • nucleic acid
    • protein coat
    • membranous envelope
  10. a.      Viral Genomes
                                                                  i.      Their genomes may consist of __(4)__
                                                                ii.      Called __virus or __virus, based on type of nucleic acid that makes up its genome
    • double-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA
    • RNA
    • DNA
  11.                                                               i.      Usually organized as a __or __molecule of nucleic acid, although the genomes of some viruses consist of multiple molecules of nucleic acid
    1.      Smallest viruses known have only __genes in their genome, while the largest have several hundred to a thousand
    2.      Bacterial genomes contain about 200 to a few thousand genes
    • single linear
    • circular
    • four
  12. a.      Capsids and Envelopes
                                                                  i.      Protein shell= __
    1.     What are the shapes?
                                                                ii.      Built from protein subunits called __
    Amount of different kinds of capsomeres are __
    • capsid
    •  Rod-shaped, polyhedral, or more complex
    • capsomeres
    • small (not numerous)
  13.                                                               i.      Rod-shaped= __viruses
    1.      __have 252 identical protein molecules arranged in a __capsid with 20 triangular facets—__
    • helical
    • Adenoviruses
    • polyhedral
    • icosahedron
    • Icosahedral
  14.                                                               i.      Some viruses have __ that aid infection
    1.      __: membranous envelope that surrounds the __of __viruses and many other viruses
    a.      Derived from __, contains__; also contain their own __
                                                                                                                                          i.      Some viruses carry a few __ molecules within their __
    • accessory structures
    • Viral envelope
    • capsids
    • influenza
    • membranes of host cell,
    •  host cells phospholipids and membrane proteins
    • proteins and glycoproteins
    • viral enzyme
    • capsids
  15. a.      __have most complex capsids
                                                                  i.      Their capsids have elongated __heads enclosing their DNA
    1.      Attached to head is a protein tail piece with fibers by which the phages attach to a bacterium
  16. Bacteriophages