Morphology

Question 1

Virion

Answer 1

Virus outside of a cell

Question 2

Morphology of a virion

Answer 2

• Core: Nucleic acid + proteins
• Capsid: Proteins
• ± Envelope: Lipid membrane + proteins

Question 3

How are virions examined?

Answer 3

By electron microscopy

• Negative contrast staining
  
  • Uranyl acetate
  • When viewing the surface
• Shadow casting
  
  • Au vapour
  • Pt vapour
  • Pl vapour

Question 4

What is shown

Answer 4

Shadow staining

• Different angles of light give different shadows

Question 5

Capsomers

Answer 5

Capsid is composed of protein units

Question 6

Nucleic acid + capsomer =

Answer 6

Nucleocapsid

Question 7

Quasihelical viruses

Answer 7

• Orthomyxo-, Paramyxo-, Rhabdovirus
• Enveloped

Question 8

Icosahedral virus

Answer 8

• 20 equilateral triangle
• Proteins arranged into capsomers
• Adeno-, parvovirus
• May have an envelope:
  
  • Herpesvirus
  • Flavivirus

Question 9

Binal virus

Answer 9

• Icosahedral head, helical tail
• Tailed bacteriophages

Question 10

Complex virus

Answer 10

• Poxvirus
• No capsomers
• Complicated symmetry

Question 11

Pleomorphic virus

Answer 11

• Arenavirus
• G-type phages
• No capsid
• Always enveloped