chapter 6 assignment
The final step in T2 bacteriophage infection results in
lysis of the bacterial cell and release of new viral particles.
Why couldn't the avian influenza outbreak be stopped in 2015?
migratory birds repeatedly introduced the virus into healthy flocks.
"Asian" influenza viruses are found in the United States primarily because
migratory birds transmit the virus to domestic flocks. Correct
The severity of symptoms of a specific strain of influenza often correlates to how deeply the virus penetrates the respiratory tract. The viral component most responsible for this aspect of infection would be the _____.
neuraminidase spikes
Once inside the host cell, viral DNA directs production of _______.
new viral particles
The correct order of the stages for phage replication are 1 = Assembly2 = Attachment3 = Transcription/replication4 = Release5 = Penetration
2, 5, 3, 1, 4
Cell culture, embryo, animals
Takes a long time to get diagnosis
Please select all the accurate statements about the importance of prions and viroids and the diseases they cause.
Viroids pose significant problems in many economically important crops. Prions may be controlled with extremely high temperatures. Prions induce abnormal folding in normal proteins. Most prion cases are not fatal and may be easily treated. Prion infections have long latent periods.
The capsid of a virus is
a protein shell that surrounds the nucleic acid.
The general steps in viral replication (in order) are
adsorption, penetration, synthesis, assembly, release.
The stage of T4 replication that involves the protein fibers on the phage and receptors on the bacterial cell wall is the
attachment stage.
The provirus state exists when
double-stranded viral DNA is integrated into host cell chromosome.
If the virus is present as a provirus in the host cell, it remains latent and never produces new virus.
false
The use of antibiotics is an effective treatment for viral infections.
false
Please select all of the following that represent viral characteristics.
have a low specificity for host cell attachment. are obligate intracellular parasites. have a 20 to 450 nanometer diameter. have machinery for synthesizing proteins. are composed of a capsid surrounding a nucleic acid core.
The inability of the HPAI H5N2 flu to move successfully from birds to humans is primarily attributable to
hemagglutinin proteins.
Live animals
Allows for viral effects on the whole organism to be observed
Polymerase chain reaction
Amplification of viral nucleic acid from a patient sample
The T-even bacteriophages such as T2 and T4 infect
Escherichia coli
If the DNA of the provirus is transcribed
one long polygenic mRNA is produced.
In phage replication
only the phage nucleic acid enters the bacterial cell.
A major difference in the replication of animal viruses and bacteriophages is the ______ step.
penetration
The stage of T4 replication that involves the injection of phage DNA is the
penetration stage.
A prophage is
phage DNA integrated into host cell genome.
In the lytic cycle of phage replication
phage nucleic acid is replicated and phage genes are expressed, making new phage protein and lysing the host cell
All viruses
possess a capsid composed of protein. have both DNA and RNA. are free-living. are reliant on a host cell for their own reproduction.
In the attachment step of phage replication
protein fibers in the phage tail attach to specific receptors on the bacterial cell wall.
The "H" and "N" designations for influenza viruses refer to
receptor spikes.
A bacteriophage initially associates with which bacterial structure?
the bacterial cell wall
Antigenic shift is a direct consequence of
the influenza virus carrying its genetic information on separate strands of RNA
The primary purposes of viral cultivation include
to isolate and identify viruses in clinical specimens. to observe viral morphology on a solid medium. to research viral structure, multiplication, genetics, and effects on host cells. to create viral antibodies against host cells for treatment of infection. to prepare viruses for vaccines.
The stage of T4 replication that involves the copying of the phage DNA and the synthesis of various phage proteins is the
transcription stage.
Prions are responsible for
transmissible spongiform encephalopathies. Mad Cow disease.Creutzfeldt-Jakob disease. Alzheimers disease.
A portion of the viral envelope comes from the cell membrane of the host cell.
true
Bacteriophage DNA directs the degradation of the bacterial host cell's DNA.
true
Enveloped viruses are usually released from the host cell by budding.
true
The polygenic mRNA codes for making one long polyprotein, which is then cleaved into the separate individual virus proteins.
true
Retroviruses have
two copies of single-stranded RNA.
Please select the characteristics that are used to identify and name viruses.
type of capsid type of envelope nucleic acid strand number type of infection area of the host cell in which the virus multiplies
Which of the following can cause a phage in the lysogenic stage to revert to the lytic stage?
ultraviolet light
The first event to occur is
viral spike proteins are inserted into host cell membrane.
Rank the following viruses from smallest to largest.
1)Yellow Fever 2)Phage T2 3)Influenza 4)Herpes 5)Poxvirus 6)Megavirus
Cell culture
Available for viruses with specific host ranges
Rapid tests
Detect virus or cytopathic effects in cells or tissue
Screening
Detection via antibodies in the patient's blood
Bird embryos
Self-contained unit with its own sterile environment and nourishment
The viral capsid
becomes completely enclosed by the region of the cell membrane into which the spikes and matrix protein are embedded.
Enveloped viruses are usually released from the host cell by
budding
Which of the following are the most useful using modern systems to classify a newly discovered virus?
capsid is icosahedral genome is RNA envelope contains particular spike proteins virus causes gastrointestinal disease
Please select criteria that are used to classify viruses.
capsid structure presence/absence of an envelope presence/absence of a capsid type of infection genetic makeup
