Study questions for Topic 3 (Structure of viruses)
Structure of viruses
- What are the functions of virion proteins?
- What does it mean to say that viral capsids are metastable?
- Know the difference between capsid, nucleocapsid, envelope, and
- What are the two rules of symmetry that instruct how virions self-assemble?
- An icosahedron has three characteristics (these are invariable). What are they?
- What does the T number describe?
- How is the simplest icosahedral virion constructed?
- If capsid proteins are not larger than 20‐60 kDa, how do you make larger virions?
- What is quasiequivalence?
- What is the function of viral envelope proteins?
- What is the difference between a structured and an unstructured envelope?
- List and describe the structural components of viruses.
- Discuss why viruses can only replicate inside living cells.
- Most of the PRRs for viral PAMPs are found in the membranes of the phagosomes, not on the surface of the cell.
- Why do you think this is?
- Name the primary cytokines produced in response to viral PAMPs and state how they function to protect against viruses.
- 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?
- Explain what 2–3–5 symmetry is, pertaining to an icosahedron.
- 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
- Describe four shapes of viruses based on their symmetry
- Briefly describe the structure of most viruses that infect humans.
- Define the following: Capsid, Capsomeres, and Nucleocapsid
- Describe how most animal viruses obtain their envelope.
- State why some bacteriophages are more complex than typical polyhedral or helical viruses.