Virology Exam 1

Lecture 3 (4/10/2013)

39 cards   |   Total Attempts: 188
  

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Cards In This Set

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What virus does attachment by projections on the capsid?
Adenovirus
How does adenovirus attach to cell?
Adenovirus attaches to the cell by protruding fibers on the capsid
What is the cell receptor for adenovirus called?
Car
What is the cell receptor and virus receptor for the influenza virus?
Cell receptor: sialic acid
virus receptor: Hemagglutinin (HA)
The structure of a terminal sialic acid moeity is recognized by what?
By the viral envelope protein hemagglutinin
How do enveloped viruses enter into the host cell?
  • Receptor-mediated endocytosis
  • fusion
How do non-enveloped viruses enter into the host cell?
  • receptor-mediated endocytosis
  • directly entering the host cel
Name different kinds of receptor-mediated endocytosis
  • clatherin-mediated endocytosis
  • caveolin-mediated endocytosis
  • non-clatherin mediated endocytosis
What are the steps of receptor mediated endocytosis
  1. Ligand (virus) binfd to specefic receptors on plasma membrane
  2. The complex diffuses along the cell membrane, until it reaches and invagination that is coated on its cyroplasmic surface by fibrous protein clatherin.
  3. The clatherin-coated pit invaginates into the cytoplasm, then it pinches off to form a clatherin coated vesicle.
  4. Clatherin coat is then lost
  5. The vesicle fuses with a small, smooth-walled vesicle near cell surface called, early endosome
  6. Early endosome is transported to near the nucleus and becomes a late endosome, the content of the late ensosome is more acidic (ph 5-6)
  7. Some ligands (viruses) dissocate from their receptors in acidic environment and are recycled back to the cell surface
  8. Late endosome fuses with lysosome.
True/ False

Early endosme inside is mildly acidic (ph 6-6.5) as a result of transport of proton into the interior of the vesicle by a membrane roton pump
TRUE
True/ False

The content of aarly endosome is more acidic than late endosome.
False

Late endosome is more acidic (ph 5-6) compared to early endosome (ph 6-6.5)
Viruses ener the cytoplasm form early or late endosomes?
Both, viruses usually enter the cytoplasm from early or late endosomes, very few enter from lysosomes.
Membrane fusion can occur where?
Fusion can occur either at the plasma membrane (phago cytosis) or from within an endosome (endoocytosis)
How close should the membranes of the virus and cell be after attachment?
The membranes of the virus and the cell must come into close contact affter attachment (receptor binding).
Viral fusion (F) protein causes the fusion of two membranes in what two different ways?
1. Fusion protein can be part of the viral receptor
2. Fusion protein can be part of a different viral protein