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Study questions for Topic 3 (Structure of viruses)

Structure of viruses

  1. What are the functions of virion proteins?
  2. What does it mean to say that viral capsids are metastable?
  3. Know the difference between capsid, nucleocapsid, envelope, and
  4. What are the two rules of symmetry that instruct how virions self-assemble?
  5. An icosahedron has three characteristics (these are invariable). What are they?
  6. What does the T number describe?
  7. How is the simplest icosahedral virion constructed?
  8. If capsid proteins are not larger than 20­‐60 kDa, how do you make larger virions?
  9. What is quasiequivalence?
  10. What is the function of viral envelope proteins?
  11. What is the difference between a structured and an unstructured envelope?
  12. List and describe the structural components of viruses.

Think Questions

  1. Discuss why viruses can only replicate inside living cells.
  2. Most of the PRRs for viral PAMPs are found in the membranes of the phagosomes, not on the surface of the cell.
  3. Why do you think this is?
  4. Name the primary cytokines produced in response to viral PAMPs and state how they function to protect against viruses.
  5. What is the function of the capsid? Why must viruses repeat the same capsid protein subunits over and over again, rather than having hundreds of different capsid proteins?
  6. Explain what 2–3–5 symmetry is, pertaining to an icosahedron.
  7. What is a structural unit? In a T = 3 virus that has three subunits per structural unit, how many total subunits form the capsid?

Short answer questions

  1. Describe four shapes of viruses based on their symmetry
  2. Briefly describe the structure of most viruses that infect humans.
  3. Define the following: Capsid, Capsomeres, and Nucleocapsid
  4. Describe how most animal viruses obtain their envelope.
  5. State why some bacteriophages are more complex than typical polyhedral or helical viruses.