Lecture Quiz 3 and 4 Flashcards
Which of the following would not be a nucleic acid form found in a viral genome?
dsRNA
dsDNA
DNA:RNA hybrid
ssRNA
ssDNA
DNA:RNA hybrid
Which of the following is an enzyme that RNA viruses encode in their genome?
DNA-dependent-DNA-polymerase
DNA-dependent-RNA-polymerase
RNA-dependent-protein-synthetase
DNA-dependent-RNA-polymerase
RNA-dependent-RNA-polymerase
RNA-dependent-RNA-polymerase
To start an experiment, you do an infection by putting 0.5 ml of a virus stock that has a titer of 6 x 107 pfu/ml onto a plate of animal cells that contains 5 x 106 cells. What is the multiplicity of infection for this experiment?
12
5
1
3
6
6
During a single growth cycle experiment, the titer of extracellular and intracellular virus drops in the first hour. What explains this observation?
The cell’s antiviral defenses prevent replication of the virus
The virus enters the cell and is uncoated.
The virus binds to the cells in the dish and can’t be released.
The virus is inactivated by antibodies in the medium.
The virus is inactivated by cellular enzymes.
The virus enters the cell and is uncoated.
What is another term for an RNA-dependent-DNA-polymerase?
Reverse transcriptase
RNA replicase
RNA polymerase II
RNA transcriptase
DNA polymerase
Reverse transcriptase
All viruses that use a negative-sense RNA genome must package which of the following proteins in their virion?
RNA methylase
scaffolding protein
RNA-dependent-RNA-polymerase
matrix protein
RNA helicase
RNA-dependent-RNA-polymerase
Which of the following is a description of a plaque?
A viral particle as seen by electron microscopy.
A skin lesion caused by a virus infection in an animal.
A region of crystallized virus particles in an infected cell.
A button of red blood cells seen in a hemagglutination assay.
A region of dead cells in a monolayer of infected cells.
A region of dead cells in a monolayer of infected cells.
The Baltimore classification system describes the pathway between a viral genome and the:
Latin classification system.
cellular polymerases.
early viral proteins.
early mRNAs.
the complementary genome sequence.
early mRNAs.
If the genome of a positive-sense RNA virus, which has been purified away from all of the virion proteins, was injected into the cytoplasm of a permissive host cell, what would happen first?
The genome would be translated by cellular ribosome’s.
The genome would be transcribed by a cellular RNA-dependent-RNA-polymerase.
None.
The genome would be transcribed by a viral RNA-dependent-RNA-polymerase.
The genome would be copied into complementary negative RNA.
The genome would be translated by cellular ribosome’s.
If the genome of a negative-sense RNA virus, which has been purified away from all of the virion proteins, was injected into the cytoplasm of a permissive host cell, what would happen first?
The genome would be translated by cellular ribosome’s.
The genome would be copied into complementary negative RNA.
None.
The genome would be transcribed by a viral RNA-dependent-RNA-polymerase.
The genome would be transcribed by a cellular RNA-dependent-RNA-polymerase.
The genome would be transcribed by a viral RNA-dependent-RNA-polymerase.
Which of the following is the best description of a syncytia?
A vesicle involved in the receptor mediated endocytosis pathway.
A fusion of two or more cells caused by viral envelope glycoproteins.
A structure between two plant cells that viruses can use for cell to cell movement.
A protein that is involved in the transport of proteins into the nucleus.
A cellular structure that viruses us to move within a host cell.
A fusion of two or more cells caused by viral envelope glycoproteins.
A fusion of two or more cells caused by viral envelope glycoproteins.
Which of the following types of genomes is most commonly found in viruses that can infect fungi?
ssRNA
ssDNA
All.
dsDNA
dsRNA
dsRNA
Which of the following is a type of nucleic acid NOT found as the genome of a virus that can infect vertebrates?
dsRNA
ssDNA
All.
ssRNA
dsDNA
all
Most viruses that infect plants have the following type of genome?
ssRNA, negative sense
ssRNA, positive sense
ssDNA, positive sense
ssDNA, negative sense
None.
ssRNA, positive sense
What is a possible explanation for why ssDNA viruses have genomes less that 10kb in size?
Larger pieces of ssDNA can not easily enter the host cell.
ssDNA can form hairpin structures because of base-pairing.
Larger pieces of ssDNA can not be replicated.
ssDNA is not as physically stable as dsDNA.
ssDNA is not transcribed by host cells.
ssDNA is not as physically stable as dsDNA.
An interesting observation is that many highly pathogenic and deadly human viruses have the following type of genome?
ssDNA, positive sense
ssRNA, negative sense
ssRNA, positive sense
ssDNA, negative sense
dsRNA
ssRNA, negative sense
Which of the following virus families have the ability to synthesize reverse transcriptase?
All.
None.
Hepadnaviruses
Retroviruses
Caulimoviruses
all
Which of the following virus families contains viruses with the longest ssRNA genome
Flaviviruses
Togaviruses
Picornaviruses
Coronaviruses
Bromoviruses
Coronaviruses
Which of the following may be a factor in explaining why viral ssRNA genomes are not usually as long as the dsDNA genomes?
It is much more difficult to package a large ssRNA genome into a capsid.
Long ssRNA molecules form too many secondary structures that inhibit replication.
Long RNA genomes are difficult to transcribe.
Long RNA genomes are difficult to translate.
Long pieces of RNA will incorporate too many lethal mutations
Long pieces of RNA will incorporate too many lethal mutations
The advantage of using a helical instead of an icosahedral nucleocapsid to package a ssRNA genome is…..
it requires fewer copies of the nucleocapsid protein than an icosahedral capsid
it better protects the genome from degradation .
it is easier to produce a helical nucleocapsid than an icosahedral capsid.
it requires a smaller protein to build than an icosahedral capsid.
it is more efficient to envelope a helical nucleocapsid than an icosahedral capsid.
it better protects the genome from degradation .
