BIO CHP 19 3

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  1. Who was a Russion biologist and what did he do?
    Ivanovski; identified the cause of tobacco mosaic disease as juice extracted from infected plants
  2. How old was Ivanovski when he discovered this?
  3. Who was a Dutch scientist and what did he do?
    Beijerinck; Suggested that tiny particles in the juice caused the disease and he name them viruses
  4. In what process do viruses multiply immeadiately after infecting the cell?
    Lytic Infection
  5. What one thing do all viruses have in common?
    They enter living cells and, once insiede, use the DNA of the infected cell to produce more viruses
  6. What happens first once a virus injects its genetic material into a cell?
    The viral genes are expressed
  7. What does the cell do to the viral DNA or RNA after the genes are expressed?
    Transcribes and translates the viral genetic infromation into viral capsid proteins
  8. What does the viral genetic program sometimes do?
    Cause the host cell to make copies of the virus and in the process the host cell is destroyed
  9. Why are most viruses highly specific?
    Because they must bind precisely to proteins on the cell's surface and then use the host's genetic system
  10. Explain what happens after bacteriophage T4 infects a cell in a Lytic infection.
    • Has a DNA core inside an intricate protein capsid that is activated by contact with a host cell
    • Injects its DNA directly into the cell
    • The host cell cannot tell difference between its DNA and virus' DNA so the cell begins to make mRNA from the genes of the virus
    • The viral mRNA is translated into viral proteins that chop up the cell DNA and shut down the infected host cell
    • The virus then uses materials of the host cell to make thousands of copies of its own DNA molecule
    • The viral DNA gets assembled into new virus particles
    • The cell lyses before long
  11. What type of infection where viruses prophages will be present many years before becoming active?
    Lysogenic Infection
  12. What happens in a lysogenic infection?
    A virus combines its DNA or RNA into the DNA of the host cell and the viral genetic information replicates along with the host cell's DNA
  13. What is a prophage?
    The viral DNA that is embedded in the host's DNA and is not active
  14. What will happen when a prophage becomes active?
    It will remove itself from the host cell DNA and direct the synthesis of new virus particles
  15. What are retroviruses?
    Viruses that contain RNA as their genetic information
  16. How did retroviruses get their name?
    "Retro" means backward and a retroviruses' genetic information is copied backward so instead of DNA->RNA it copies RNA->DNA
  17. What is a VERY common disease retroviruses are responsible for some types of?
  18. What do retro viruses take advantage of in the host cell?
    • Respiration
    • Nutrition
    • All other functions that occur in living things
  19. What are viruses considered as and why?
    Parasites because like parasites, viruses depend upon other living organisms for their existence and harm that organism in the process
  20. Are viruses alive?
    No, but they have many characteristics of living cells
  21. Why are viruses not considered to be living?
    Because they aren't made of cells or able to live independently
  22. What can viruses do after infecting a cell?
    • Reproduce
    • Regulate gene expression
    • Evolve
  23. Why couldn't viruses have been the first living things?
    Becauses they live off of other living organisms so they had to evolve after living organisms did
  24. How may have the first viruses evolved?
    From the genetic material of other living cells
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BIO CHP 19 3
2012-04-18 02:51:28

JUST DO IT!!! ;)
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