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VIROLOGY EXAM 2 QESTIONS AND ANSWERS
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VIROLOGY EXAM 2 QESTIONS AND ANSWERS
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VIROLOGY EXAM 2 QESTIONS AND ANSWERSWhich of the following structures found on E. coli cells is required for infection with a
ssRNA phage?
a) Cell wall
b) Lipopolysaccharide
c) F-pili
d) Cell surface receptor
e) All of the above are required. - Answers -c) F-pili
The discovery of the ssRNA phages was useful to scientists working on which of the
following processes:
a) Structure of ribosomal RNA
b) Translation of messenger RNA
c) Structure of proteins
d) Transcription of messenger RNA
e) Replication of DNA - Answers -b) Translation of messenger RNA
Why are ssRNA phages used as an index organism to detect the presence of
pathogenic enteroviruses in the sewage treatment process?
a) The RNA phage are smaller than the pathogenic viruses.
b) The RNA phage are easier to inactivate than the pathogenic viruses.
c) The RNA phage are more stable than the pathogenic viruses.
d) The RNA phage are easier to quantify using a plaque assay than the pathogenic
viruses.
e) The RNA phage are easier to see with an electron microscope than the pathogenic
viruses - Answers -d) The RNA phage are easier to quantify using a plaque assay than
the pathogenic viruses.
Site directed mutagenesis of the MS2 genome was carried out to abolish the MJ stem
structure that is just upstream of the start codon of the replicase gene. Which of the
following describes the result of this experiment?
a) The coat protein was unable to bind to the viral genome.
b) The maturation protein was unable to bind to the stem-loop.
c) The ribosome could no longer bind to the start codon for the replicase gene.
d) The replicase protein was unable to bind to the viral genome.
e) Translation of replicase gene increased in the absence of coat protein translation. -
Answers -e) Translation of replicase gene increased in the absence of coat protein
translation.
What is the function of Host Factor during the replication of the Qβ RNA genome?
,a) It delays the folding of the RNA into its final secondary structure.
b) It makes the 3' end of the genome more accessible to the replicase enzyme.
c) It adds a non-template A nucleotide to the 5' end of the minus strand.
d) It facilitates binding of the replicase protein to the coat protein start codon.
e) It prevents binding of the replicase enzyme to the 5' end of the genome. - Answers -
b) It makes the 3' end of the genome more accessible to the replicase enzyme.
In the ssRNA phage MS2, binding of the coat protein to which of the following RNA
structures acts to initiate packaging of the viral RNA into the capsids.
a) The 5' end of the genome
b) The 3' end of the genome
c) The MJ stem loop
d) The start codon of the coat protein gene
e) The operator stem loop - Answers -e) The operator stem loop
In the ssRNA phage MS2, the replicase protein binds to the start codon of the coat
protein gene. Which of the following describes the reason for this binding?
a) It prevents replication and translation from occurring simultaneously.
b) It initiates synthesis of the minus-strand copy of the genome.
c) It enhances binding of the ribosome to the coat protein gene.
d) It disrupts the stem-loop structure that prevents replication of the viral genome.
e) It exposes the 3' end of the genome which allows the replicase to begin RNA
synthesis. - Answers -a) It prevents replication and translation from occurring
simultaneously.
The viral polymerase complex from the RNA phage Qβ contains which of the following
host cell proteins?
a) Host Factor
b) S1 ribosomal protein
c) EF-Tu translational factor
d) EF-Ts translational factor
e) All of the above are part of the complex. - Answers -e) All of the above are part of the
complex.
In the ssRNA phage Qβ the synthesis of the plus strand RNA genome from the negative
strand template does not require the ribosomal S1 protein. Which of the following
explains why?
a) The minus strand is shorter and takes less time to replicate
b) The minus strand lacks the secondary structure that prevents replication.
c) There is no competition between binding of the replicase enzyme and the ribosome.
d) The replicase enzyme is more processive when copying the minus strand.
, e) The minus strand has a lower GC content than the plus strand. - Answers -c) There
is no competition between binding of the replicase enzyme and the ribosome.
In the ssRNA phage MS2, the maturation protein is only produced after which of the
following events occurs?
a) The synthesis of the negative strand of the viral genome.
b) The synthesis of the positive strand of the viral genome.
c) Packaging of the viral genome into new capsids.
d) Translation of the coat protein.
e) Folding of the newly synthesized genome into the stable secondary structure. -
Answers -b) The synthesis of the positive strand of the viral genome.
The replicase enzyme of the ssRNA phage Qβ has been used by scientists to do which
of the following?
a) Synthesize RNA molecules from a DNA template.
b) Measure small amounts of target RNA molecules in a sample.
c) Measure the levels of pathogenic viruses in drinking water.
d) Amplify DNA molecules in a sample.
e) Fuse two pieces of RNA together. - Answers -b) Measure small amounts of target
RNA molecules in a sample.
Replication and translation can occur simultaneously on a single molecule of genomic
RNA from the ssRNA phage MS2. - Answers -FALSE
During the replication cycle of the ssRNA phage MS2, the lysis gene can not be
translated in the absence of translation of the coat protein gene. - Answers -TRUE
Replication of the RNA genome by the replicase enzyme from the phage Qβ is
completely independent of host cell proteins. - Answers -FALSE
The translation of the maturation protein from a newly synthesized positive strand
genome in the phage MS2 depends on delayed folding of the RNA into its final
secondary structure. - Answers -TRUE
Which of the following was used to distinguish different bacteriophages before the
development of the electron microscope in the 1930's?
a) Western blot
b) DNA sequence
c) DNA restriction analysis
d) X-ray crystallography
e) Plaque morphology - Answers -e) Plaque morphology
What distinguishes the small bacteriophage φX174 from many other bacteriophages?
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