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Flashcards in Viruses Deck (36)
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1

percentage of infectious diseases that are from virus

60 %

2

viral infections cause or contribute to what percentage of human cancers

20%

3

are viruses microorganims

no they need host to survive - obligate intracellular

4

genomic material of virus

DNA or RNA but not BOTH

5

what viruses have both DNA and RNA

giant virus aka giruses

6

what is the core of virus

nucleic acid and protein coat

7

what is a virion and another name for it

completely infectious particle

viable virus

8

some properties of viruses

diversity is enormous
limited host range (usually only one cell type)
cell tropism
survival dilemma

9

what does virus having cell tropism mean

they will only infect certain types of cell

10

typical size of virus

typically 0.2 micrometers

11

what do you call viruses/virion that do not have an envelope

they are described as being naked

12

what is the capsid of virions made of and its importance

protein coat
protection

13

protein shell around nucleic acid is called

nucleocapsid

14

what do viruses need to make their proteins aggregate into a capsomer

nothing --- self assembly
they do not need energy

15

two main types of capsid symmetry

helical
icosahedral (perfectly stable structure)

16

most animal viruses and most viruses that cause diseases in human have what type of capsid

icosahedral

17

what do all human viruses with a helical capsid have

an envelope

18

describe the structure of a helical capsid

rigid or flexible
length controlled by NA

PS it goes NA --> capsomer (subunit of capsid) --> capsid

19

describe the structure of a icosahedral capsid

20 facets (each an equilateral triangle)
12 vertices
because of the axes has 5:3:2 symmetry

20

what are the two different types of capsomers for icosahedrals

pentons - are at the points of the triangles aka vertices
hexons - make up the face of the equilateral triangle aka the facets

21

since all icosahedral capsids have 20 facets and 12 vertices, where does the size differential come from?

increasing the size of the hexons increases the size of the icosahedral capsid

22

what is the viral envelope composed of

2 lipid layers interspersed with protein molecules

23

virus does not have any lipid so where does it gets the lipid for its envelope

host

24

so where does the material for the viral envelope come from

host (lipid) and virus (proteins)

25

what does the viral envelope surround

nucleocapsid (baggy or shrink wrapped)

26

what type of infections are viral envelopes associated with

persistent infections

27

describe enveloped viruses interaction with alcohol and with the immune system

enveloped viruses have lipids so it is easy to eliminate them (more susceptible) with alcohols and once the surface protein on the envelope is eliminated, virus cannot carry out their function

on the other hand, enveloped viruses are harder to recognize by the immune system so that is its advantage

28

two major proteins on viral envelope of influenza virus

hemagglutinin (surface glycoprotein)
neuraminidase (surface spikes)

29

function of the viral envelope major proteins in influenza virus

Hemagglutinin (surface glycoprotein) - Attaches to sialic acid residues of host cell surface

Neuraminidase (surface “spike”) - Aids in release of virus from host cell

30

where are nucleoproteins found

core of virus