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63 Cards in this Set

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  • Back
What are the two basic components of a virus?
Genome (RNA or DNA) surrounded by a protective coat.
Viruses are obligate ____ ____.
intracellular parasites
In what environment will viruses multiply?
Only in living cells.
Viruses are dependent on host cell machinery for what two functions?
1) protein synthesis
2) stored cellular energy
How do viruses make use of host cells?
degrade cells and use cellular components
Viruses are assembled from what?
simple, repeating, self-assembling subunits
def - Capsid
protein coat
def - Virion
complete virus particle
What is found in the core of a virus?
nucleic acid (DNA or RNA), core proteins
What is the function of a virus capsid?
protect genome
Capsids are (symmetrical/asymmetrical).
symmetrical (helical, icosahedral or complex)
Capsids function in attachment of virus to ____ ____.
host cell
Capsids are composed of capsomeres, which are ____ ____.
protein polypeptides
def - Nucleocapsid
core + capsid
Where are the lipids in a lipid envelope derived?
from host cell membranes
Glycoproteins embedded in the lipid envelope interact with host cells and the environment. Name two important functions of these glycoproteins.
1) responsible for viral attachment
2) target for host immune response (antigens)
There may be a protein layer between the capsid and envelope. What makes this layer?
matrix or tegument proteins
Name three physical characteristics of naked capsids.
1) stable
2) resistant to heat, pH, drying, detergents, proteases
3) released by cell lysis
Describe three basic transmission characteristics of naked capsids.
1) easily spread
2) longer survival time
3) may survive gut
Name three physical characteristics of enveloped viruses.
1) labile (easily damaged)
2) susceptible to heat, pH, drying, detergents
3) released by budding or cell lysis
Describe three basic transmission characteristics of enveloped viruses.
1) must remain wet
2) close contact, droplets
3) destroyed in gut
Do capsids with helical symmetry have envelopes?
no
What units make up the structure of a helically symmetrical capsid?
RNA helix with associated nucleoproteins
Name two examples of viruses with helical symmetry.
1) TMV
2) Filoviruses (Ebola, Marburg)
What are some characteristics of icosahedral symmetry?
repeating subunits (pentamere, capsomere)
self-assembled subunits from a few proteins (5)
encloses largest possible volume
very strong
Can complex virus structures be defined by a mathematical equation?
nope
Name two viruses with complex structure.
1) Pox virus
2) T4 Bacteriophage
How large are poxviruses?
>300 nm
Name four virion morphologies.
1) icosahedral
2) spherical
3) rodlike
4) bullet
5) filamentous
Three families with naked icosahedral morphology.
1) Papova-
2) Picorna
3) Adenoviridae
Name two families with enveloped icosahedral morphology.
1) Herpes-
2) Togaviridae
Are there any viruses of human medical importance with naked helical morphology?
nope.

plant viruses (TMV, Bacteriophage M13)
Name three families with enveloped helical morphology.
1) Orthomyxo-
2) Paramyxo-
3) Filoviridae
Name three families with complex morphology.
1) Poxviridae
2) Bacteriophage T4
3) Lambdavirus
How do viral genomes compare to prokaryotes and eukaryotes in size?
small!
Which virus has the smalles genome?
parvovirus (5.5 kbp)
Name three viruses with the largest genomes.
1) pox virus (195 kbp)
2) cytomegalovirus (239 kbp)
3) mimivirus (>800 kbp)
What is the size range for bacterial genomes?
900 kbp to 5,000 kbp
What is the size range for human chromosomes?
50,000 kbp to 245,000 kbp
If a virus has an RNA genome, what are the three varieties it may present?
1) Single stranded RNA (- or + sense, + = coding)
2) Double stranded RNA
3) Segmented (several pieces of RNA)
If a virus has a DNA genome, what are three variations?
1) single stranded (only Parvociridae)
2) double stranded (most)
3) linear (most) or circular (Papovaviridae)
How is the name of a virus family indicated?
-iridae (e.g. Herpesviridae)
How is the name of a virus sub-family indicated?
-irinae (e.g. alphaherpesvirinae)
Viruses are grouped into families based on what four criteria?
1) enveloped v. naked virions
2) genetic material (RNA v. DNA, ds v. ss, +ssRNA v. -ssRNA)
3) capsid symmetry
4) size
Picorna - genome? enveloped or naked?
+RNA, naked
Calici - genome? enveloped or naked?
+RNA, naked
Toga - genome? enveloped or naked?
+RNA, enveloped
Corona - genome? enveloped or naked?
+RNA, enveloped
Rhabdo - genome? enveloped or naked?
-RNA, enveloped
Filo - genome? enveloped or naked
-RNA, enveloped
Orthomyxo - genome? enveloped or naked?
-RNA, enveloped
Paramyxo - genome? enveloped or naked?
-RNA, enveloped
Bunya - genome? enveloped or naked?
-RNA, enveloped
Arena - genome? enveloped or naked?
-RNA, enveloped
Reo - genome? enveloped or naked?
+/-RNA, double capsid

reo=wierdo
Retro - genome? enveloped or naked?
+RNA via DNA, enveloped
Pox - genome? enveloped or naked?
DNA, enveloped
Herpes - genome? enveloped or naked?
DNA, enveloped
Hepadna - genome? enveloped or naked?
DNA, enveloped
Parvo - genome? enveloped or naked?
ssDNA**, naked
Polyoma - genome? enveloped or naked?
DNA, naked
Papilloma - genome? enveloped or naked?
DNA, naked
Adeno - genome? naked or enveloped?
DNA, naked