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Viruses ((Animal Viruses (presence or absence of a membranous envelope…

- - - - complementary RNA strands also function as mRNA which is translated into glycoproteins and viral envelope
      - 4.new copies of viral genome RNA are made
      - viral genome functions as template for synthesis
      - vesicles transport envelope glycoproteins to the plasma membrane
      - 2.capsid and viral genome enter cell
      - capsid assembles around each viral genome molecule
      - glycoproteins bind to specific receptor molecules
      - each new virus buds from the cell
    - - retroviruses (most complicated)
        
        reverse transcriptase (HIV)
        
        molecules released into cytoplasm
        
        provirus
  - - - candidates for original source of viral genomes
        
        plasmds
        
        small circular DNA molecules found in bacteria and unicellular eukaryotes called yeasts
        
        transposons
        
        DNA segments that can move from one location to another within a cell's genome
  - - - Process
        
        dissemination from a small, isolated human population
        
        spread of existing viruses from other animals
        
        1.mutation of existing viruses
        
        mutation when passed from one host species to another
  - - - horizontal transmission
      - vertical transmission
  - - - act very slowly (incubation of at least 10 years)
      - virtually indestructible
        
        misfolded form of a protein normally present in brain cells
        
        somehow convert normal protein molecules to the misfolded
        
        several prions then aggregate into a complex that can convert other normal proteins to prions
- - - - polyhedral
        
        icosahedral
      - more complex shapes
      - rod shaped
        
        helical
    - - derived from membranes of host cell
        
        contain host cell phospholipids and mebrane proteins
        
        contains proteins and glycoproteins of viral origin
      - some viruses carry a few viral enzyme molecules within their capsides
        
        many of the most complex capsides are bacteriophages aka phages
  - - - smaller than a ribosome
    - - barely visible under light microscope
  - - - based on kind of nucleic acid
    - - .
        
        circular molecule
    - - based on kind of nucleic acid
    - - .
        
        single linear
- - - - inject DNA
        
        DNA proteins commandeer host and reprogram the cell to copy viral genome and manufacture viral proteins
        
        host provides nucleotides
      - fusion of viral envelope with host plasma membrane
        
        .
      - endocytosis
        
        .
        
        RNA Virus use virally encoded RNA polymers that can use RNA as a template
        
        viral nucleic acide molecules and capsomers spontaneously self-assemble into new virus
        
        viral progeny exit the cell and have the potential to infect additional cells, spreading the viral infection
  - - - Culminates in death of the host cell
        
        synthesis of viral genomes and proteins
        
        self assembly
        
        entry of phage DNA and degredation of host DNA
        
        release
        
        bacterium lyses and releases phages produced in teh cell
        
        each phage can then infect a healthy cell
        
        attachment
    - - Coexist with host (allows replication of phage genome without destroying the host)
        
        alter host phenotype
        
        can cause host bacteria to make toxins
        
        prevent transcription of most other prophage genes
      - major reason why phages haven't exterminated all bacteria
- - - - favors bacterial mutants with surface proteins that are no longer recognized as receptors by particular type of phage
    - - the phage DNA is id'ed as foreign and cut up
    - - spacer DNA and palindrom sequences
        
        nucleaoses CAS preoteins can identify and cut phage DNA
  - - - resemble nucleosides