BIO 116 Ch. 4

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  1. Virus:
    parasites that need to enter and take control of a cell to replicate
  2. What do all viruses have as their genetic material?
    DNA and RNA
  3. What does the genetic material in a virus contain information for?
    how to make viral proteins and the viral protein coat/envelope
  4. What does the protein coat/envelop do for a virus?
    it protects the genetic material from the host organism
  5. What do viruses depend on their host cells for?
    • energy production
    • protein synthesis
    • DNA/RNA replication
  6. What are the 4 main places for viruses to enter your body?
    • respiratory tract (like breathing)
    • digestive tract (eating)
    • anal/genital tract (vagina, anus, p-hole)
    • breaks in skin (like a cut)
  7. primary site:
    an initial infection at the point of entry into your body
  8. secondary site:
    new site of infection after the initial infection site
  9. What are the 4 stages of a virus infection cycle?
    • 1) virus is bound to the cell surface
    • 2) virus enters and is uncoated
    • 3) virus is incorporated into the host cell's DNA
    • 4) new virus particles are assembled
  10. receptor protein:
    protein on the cell surface that binds with the virus protein
  11. lytic virus:
    kills the host cell after assembling the new virus particles
  12. nonlytic virus:
    doesn't kill the host cell after assembling the new virus particles
  13. latent virus:
    the virus inserts its genetic material (DNA) into the host cell’s chromosome and remains hidden, not producing new viral particles, until it's reactivated
  14. reactivated virus:
    a virus that was hidden and inactive is reactivated to start making new virus particals
  15. Do antibiotics work on viruses? Why or why not?
    NOPE because viruses aren't technically living organisms
  16. How can we typically treat a virus?
    just take some medications to ease the symptoms, get plenty of rest, and let the virus run it's course
  17. What is the best defense against a virus?
    education and prevention (vaccines)
  18. What do antiviral medications do?
    try to exploit weak points in a viruses life cycle and interrupt it
  19. retrovirus:
    their genetic material is RNA and they must convert their genetic message into DNA instead of DNA -> RNA (the normal way)
  20. Gag genes:
    proteins that are part of the protein coat, which the immune system cells may be able to mount a response against
  21. Reverse transcriptase:
    responsible for the reverse transcription or copying of the viral RNA into a DNA version
  22. Protease:
    responsible for the maturation of viral proteins once new viruses are made and ready to leave the host cell
  23. Integrase enzymes:
    help the DNA copy of the virus to integrate or enter and splice into the host cell’s DNA
  24. pol genes:
    enzymes that are involved in the copying of genetic material
  25.  Env proteins:
    (envelope proteins) these proteins will become a part of the membrane that surrounds new core virus particles
  26. What are the two important env proteins in HIV?
    gp120 and gp41
  27. Where is HIV-2 isolated in?
  28. What's is HIV's host cell receptor called?
  29. Which HIV envelope protein binds to the HIV receptor?
  30. What is the primary target of HIV?
    T-helper cells
  31. What must there be for HIV to enter the cell?  What does it bind?
    co-receptor; protein called gp-41
  32. When HIV infects a T-helper cell, what are the two things it could do?
    • spread viral particles and kill the cell
    • T-helper cell will latently harbor the cell for reactivation
  33. When HIV infects a macrophage, does it kill the macrophage after producing viral particles?
  34. Why can't HIV infect a dendritic cell?  What does this cause?
    it has a surface receptor that hold HIV on the surface; the dendritic cell brings HIV to the lymph nodes where it infects new T-helper cells
  35. What does the ELISA test for?
    HIV antigens/antibodies
  36. How accurate is the ELISA test?
    over 99.9% accurate (less that 1/1000 are mistaken for false negative/positive)
  37. If the ELISA test comes back positive, what do they do to double-check?
    they use the Western blot test to test for HIV-specific antibodies
  38. How long could it take for someone to make antibodies against HIV?
    up to 6 months
  39. What does the PCR test look for?
    HIV DNA in infected cells OR HIV RNA in virus particles 
  40. What are the three reasons that HIV might evade the immune system?
    • latency
    • high mutation rate
    • cell-to-cell transfer
  41. cell-to-cell transfer:
    a virus is passed directly from cell to cell and spends no time at all outside the cell (where it can be detected)
  42. How does AZT work against HIV?
    it's a mutated form of thymidine and takes the place of it so that DNA can't be copied
  43. nucleoside reverse transcriptase inhibitors (NRTI):
    drugs that inhibit the reverse transcriptase to copy and spread HIV
  44. What is a bad side effect of AZT?
    it gets into the host cell's DNA and kills the host cell
  45. protease inhibitors:
    drug that blocks the enzyme called protease and makes HIV inactive
  46. Where did HIV-1 come from?
  47. Where is HIV-2 only found?
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BIO 116 Ch. 4

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