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Chapter 19 (Viral Replication (HIV replication cycle (Double strand DNA…

- - - - discovered disease could be transferred from plant to plant by rubbing sap extracted from diseased leaves to non infected leaves
      - After an unsuccessful search for an infectious particle he concluded that it was a small bacteria that was invisible under microscope
    - - Tested Mayers hypothesis: ran infected sap through a filter designed to remove bacteria, but still found TMD after filtration
      - Conclusion: still agreed with Mayers
    - - 1st to voice concept of virus
        
        imagined a smaller simpler participle than a bacterium
      - Carried out experiments and tested out the hypothesis
      - discovered pathogen was replicating because it did not lose potency from plant to plant
      - disease could not be cultivated in test tubes/ petri dishes unlike bacteria
      - Conducted a filtration system with infected TMD sap and was still found after filtration.
    - - Confirmed with Beijerinck virus concept
      - Crystallized the virus particle with electron microscope
  - - - have a genetic program
      - infect all types of species every form of life
      - Mobile Genetic Elements
        
        Candidates for their original source
        
        Plasmids
        
        Transpoons
        
        Capable of moving around genome and transfer around
        
        some viruses have genes identical to host
- - - - Double strand
      - Single strand
    - - Single strand
      - Double
  - - - Capsomeres: large protein subunits that build capsids
      - variery of type of protein is small
    - - Adenovirus
    - - Tobacco Mosaic Virus
    - - Bacteriophage (phage): virus that infects bacteria with its long tail fibers
      - T4
    - - Influenza Virus
  - - - DNA single or double stranded
      - RNA is mainly in plant and some phages
        
        3 types single strand RNA
        
        RNA V
        
        serves as template for mRNA synthesis
        
        RNA transcribed to complimentary RNA strands, are mRNA template for genome synthesis
        
        Requiire RNA-RNA sysnthesis
        
        viral enzyme enclosed with viral genome
        
        exit cell withou killing it
        
        RNA VI
        
        Retrovirus:most complicated replication cycle
        
        Enzymes: reverse transcriptase
        
        transcribes an RNA templae to DNA
        
        HIV:Human Immunodeficiency Virus
        
        AIDS:Acquired Immunodeficiency Syndrome
        
        Provirus:integrated viral DNA, permenent resident
        
        RNA IV
        
        serves as mRNA directly and then translated to viral protein immediately after infection
- - - - West Nile can infect birds humans and horses
  - - - Some enter cell by infection by tail fibers/endocytosis
  - - - allows replication of phage genome w/o destroying cell
      - DNA is incorporated in host chromosome:prophage
      - Normal replication process continues to transmit daughter cells with prophage
    - - Virulent Phage: phage that only replicates by lytic cycle
      - results in death of the cell
      - refers to the last stage of the cycle
    - - lambda T4
  - - - Interspaced
      - Short
      - Regulatory
      - Palindromic
      - Repeats
      - Clustered
      - 2 repeats system
      - each short RNA strand binds to Cas protein. uses it as a homing device to to identify invading ohage
      - RNA transcribed to short RNA strands. RNA is complementary to DNA of invading phage
      - Complementary RNA binds to DNA from invading phage Cas protein will then cut phage DNA
      - 1.Phage infection triggers transcription of CRISPR region in bacterial DNA
        
        region consist of DNA of phage that have previously infected bacteria
      - After being cut entire phage DNA molecule is degraded
  - - - Translated to capsid proteins in cytosol
      - glycoproteins for viral envelope in ER and Golgi apparatus
    - - Used to enter cell
      - derived from host cell plasma membrane
      - Temporarily cloaked in nuclear membrane from host and later shed it off in cytoplasm and gets a new envelope from Golgi Apparatus
        
        Herpesvirus
        
        copies of viral DNA can stay in nuclei as mini chromosomes and flare up
- - - - Medical care can help most before virus has entered
    - - Several drugs have been made to attack HIV virus
  - - - Zika Virus
      - Chikungunya
      - Ebola Virus
    - - Dissemination from a small to large population
        
        humans are responsible for spread due to advancements in technology
      - Virus host range expanding
        
        Genetic mutations allow species jumping
      - Mutation of Existing Viruses
        
        Viruses do not proofread or correct so there is new types of the same virus
        
        people who were immune to old virus are not immune to new one
    - - Horizontal Transmission
        
        Infected by external source
        
        Damaged plant are more susceptible for infection
      - Stunted growth and discoloration, and brown spotted
      - Vertical transmission
        
        Inherits from parent
      - Once virus has enters cell it spreads in plant by plasmodesmata allowing proteins/genome to spread
  - - - Long incubation period, allowing to be unnoticed
    - - not affected by heat
      - No cures