2. Lecture

Question 1

describe the morphology of a virion

Answer 1

core: nucleic acid + proteins
– capsid: proteins
– ± envelope: lipid membrane + proteins

Question 2

what is seen with electromicroscopy

Answer 2

Ultra thin sections
• 0.1-0.5 μm
• W and U salts
• inner structure
Negative contrast staining
• uranyl acetate
• surface
Shadow-casting
• Au, Pt, Pl vapor
• shape, symmetry, 3D

Question 3

what is the morphology of viruses determined by

Answer 3

the capsid

Question 4

capsids are composed of

Answer 4

composed of protein units:

capsomers

Question 5

Helical capsid

Answer 5

nucleic acid + capsomers:
nucleocapsid
No animal pathogen

Question 6

Quasihelical capsid, examples

Answer 6

• (Orthomyxo-, Paramyxo-, Rhabdovirus…)
• Always enveloped
• cannot measure diameter w/o enveloe → virtual diameter

Question 7

Icosahedral capsid

Answer 7

20 equilateral triangle
Proteins arranged into capsomers
(di-, tri-, penta-, hexamers)

Question 8

Icosahedral (cubic) virus, examples

Answer 8

20 equilateral triangle
can look like football
Proteins arranged into capsomers: (Adeno-, Parvovirus)
May have envelope: (Herpes-, Flavivirus)

Question 9

Binal capsid

Answer 9

icosahedral head + helical tail

tailed bacteriophages

Question 10

Complex capsid, example

Answer 10

(Poxviruses)
complicated symmetry, no typical mophology (bc. no capsomeres)

dont know if enveloped or not

Question 11

Pleomorphic virus type

Answer 11

Arenavirus, G type phages
No capsid
Always enveloped

hard to describe shape