Viruses

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Author:
sweetz2go
ID:
130653
Filename:
Viruses
Updated:
2012-01-25 23:03:02
Tags:
biology
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Description:
bio 1215
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  1. virus are non-living. why?
    they cannot replicate on its own, need a host cell to provide metabolic machinery, no signs of life on its own, the living cell has RNA as primary
  2. what are the 4 types of structural diversity of viruses?
    Tocacco Mosaic virus(cold-like symtoms, can cause ammonia) , Adenovirus, Influenza virus, Bacteriophage

  3. What are the common structure of viruses?
    Genetic material: either RNA or DNA

    Capsid: protein "shell" composed of spherical subunits called capsomeres(parts of capsid)

    Envelope: covering of viruses that infect animal cells, envelope composed of membrane of host cell and viral glycoproteins

  4. What is the function of capsid?
    surrounds genetic material and protects it
  5. What is function of the envelope?
    -are used to help viruses enter host cells
  6. Describe the structure of HIV
    • reverse transcriptase: enzyme, RNA to DNA
    • capsomere of capsid: protects genetic material
    • Intergrase: helps insert into host cell
    • Protease: make viral proteins
    • Identical RNA: back up, muliply faster

  7. How does HIV spread so rapidly?
    • -breastfeeding
    • -needles (drug use)
    • -vaginal and anal sex
    • -blood transfusions
  8. Explain how HIV reduces the immune system of an infected person.
    1. Binding and Fusion: HIV begins its life cycle when it binds to a CD4 receptor and one of two co-receptors on the surface of a CD4+ T- lymphocyte. The virus then fuses with the host cell. After fusion, the virus releases RNA, its genetic material, into the host cell.

    2.Reverse Transcription: An HIV enzyme called reverse transcriptase converts the single-stranded HIV RNA to double-stranded HIV DNA.

    3. Integration: The newly formed HIV DNA enters the host cell's nucleus, where an HIV enzyme called integrase "hides" the HIV DNA within the host cell's own DNA. The integrated HIV DNA is called provirus. The provirus may remain inactive for several years, producing few or no new copies of HIV.

    4. Transcription: When the host cell receives a signal to become active, the provirus uses a host enzyme called RNA polymerase to create copies of the HIV genomic material, as well as shorter strands of RNA called messenger RNA (mRNA). The mRNA is used as a blueprint to make long chains of HIV proteins.

    5.Assembly: An HIV enzyme called protease cuts the long chains of HIV proteins into smaller individual proteins. As the smaller HIV proteins come together with copies of HIV's RNA genetic material, a new virus particle is assembled.

    6. Budding: The newly assembled virus pushes out ("buds") from the host cell. During budding, the new virus steals part of the cell's outer envelope. This envelope, which acts as a covering, is studded with protein/sugar combinations called HIV glycoproteins. These HIV glycoproteins are necessary for the virus to bind CD4 and co- receptors. The new copies of HIV can now move on to infect other cells.

  9. what are the symptoms of AIDS?
    • parasitic infection of digestive tract, kaposi's saroma( a kind of cancer in blood vessels)
    • - blemishes, secondary infections, fever, enlarged lymph glands, skin legions and rash, cough, severe weight loss, loss of appetite and fatigue
  10. why are there no vaccines for aids?
    virus is constantly mutating in reverse transcriptase; everytime it does this it makes errors and so genetic material changing which creates a new strain of virus
  11. why are antibiotic useless against viruses?
    they are not bacteria, antibiotics target metobolic machinery like cellular chemical reactions but viruses have no metabolic machinery
  12. The progress of Aids disease is slowed down by? (2)
    1. reverse transcriptase inhibitors: shuts off viral RNA from becoming viral DNA

    2. Protease inhibitors: targets protease enzyme and stops it from making glycoproteins.

    * new research, inserted genetic material that codes for antibody and visus acting like vector

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