What is the function of the structural elements of a virus?
answer
To package and protect the viral genome
question
Lysogenic viral DNA which has integrated into the host genome is referred to as
answer
a prophage.
question
Which of the following events might trigger induction of a temperate bacteriophage?
answer
Exposure to UV light
question
How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
answer
The host cell dies during the lytic stage.
question
What is the fate of the prophage during the lysogenic stage?
answer
It is copied every time the host DNA replicates.
question
In which stage is the viral DNA introduced into the cell?
answer
Penetration
question
In which stage does formation of mature viruses occur?
answer
Assembly
question
The host DNA is usually degraded during which stage?
answer
Biosynthesis
question
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
answer
The virus would not be able to infect new hosts.
question
What is the most likely etiology (cause) of this disease?
answer
prion
question
How did this man most likely become exposed to this disease agent?
answer
He is likely to have been exposed while hunting elk in Colorado during his childhood.
question
Is this disease contagious?
answer
There is no evidence that prion diseases are contagious. All have been associated with consuming tissues (especially neurological tissues, such as brain and spinal cord) of affected animals.
question
Which test confirmed the presence of this prion disease?
answer
brain scan
question
What is the typical incubation period for prion diseases?
answer
decades
question
Which of the following is an essential component of all viruses?
answer
capsid
question
Which of the following statements describes a generalist virus?
answer
It infects many kinds of cells in many different hosts
question
The envelope found in some virus particles differs from the cytoplasmic membrane of cells in that __________.
answer
it does not perform the physiological functions carried out by the cytoplasmic membrane
question
In what ways do viruses differ from other pathogens?
answer
Viruses lack cytoplasm and organelles.
question
The outermost layer of a virion fulfills which of the following functions of the virus?
answer
both protection and recognition
question
A(n) ________ is a virus that infects bacterial cells
answer
bacteriophage
question
A drug targets chitin. Which type of pathogen should this drug be effective against?
answer
fungi
question
A pathogen that has chitin in its cell wall would also have _________
answer
Ergosterol
question
A person has a suspected lung infection. A sputum sample is Gram stained, but no bacteria are visible. However, bacterial colonies do grow after a prolonged incubation. The patient is successfully treated with an antibiotic regimen that includes isoniazid. Why were no bacteria visible after the initial staining reaction?
answer
Mycolic acids in the wall of this pathogen resist uptake of the Gram stain
question
Students identified RSV and influenza as possible causes of Uncle Luis' lung infection. In terms of characteristics used to classify viruses, what distinguishes these two viruses?
answer
Genome structure
question
Which of the following is CORRECT regarding the viral envelope?
answer
It is composed of cellular phospholipid membrane, cellular and viral proteins.
question
What is a virion?
answer
a single virus particle outside a cell
question
Which of the following infectious particles is most susceptible to damage?
answer
enveloped virus
question
The infectious cycles of enveloped animal viruses and temperate bacteriophages are most similar because __________.
answer
the infected cell may live for a long time
question
Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4?
answer
entry and release
question
A(n) ________ is a bacterial virus which is integrated into the host cell DNA.
answer
prophage
question
Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but NOT in the lysogenic cycle?
answer
digestion of host DNA
question
Why is lysogeny advantageous to a bacteriophage?
answer
the genetic material of the bacteriophage is amplified many times over that seen in a lytic phage
question
Naked capsid animal viruses are commonly released from the infected cell by ________, a process the host cell does not survive.
answer
lysis
question
Which of the following membranes can give rise to a viral envelope?
answer
the nuclear and cytoplasmic membranes and the endoplasmic reticulum
question
How is the HIV provirus different from a lambda-phage prophage?
answer
The HIV provirus is integrated permanently into the host cell's DNA
question
The process known as ________ is a mechanism of release for enveloped viruses.
answer
budding
question
Both viruses and carcinogenic chemicals can cause tumors by __________.
answer
disruption of control over the rate of cell division
question
Tumors invade other organs and tissues in a process called
answer
metastasis.
question
Viruses can be grown in all of the following EXCEPT __________
answer
sterile nutrient agar
question
In a plaque assay, a microbiologist counts 20 plaques on a plate. How many plaque-forming units can be assumed to have been present in the original bacterium-virus mixture on the plate, if there was no dilution of the mixture prior to plating?
answer
20
question
Which of the following laboratory procedures is used for culturing animal viruses in the laboratory?
answer
both cell cultures and embryonated eggs
question
Plaque assays are used for
answer
determining the density of phage in a culture.
question
Which of the following is a feature shared by viruses and living organisms?
answer
possession of a genome that directs synthesis of materials necessary for replication
question
Which of the following is NOT true about viroids?
answer
A viroid causes chronic wasting disease in deer and elk.
question
Viroids infect
answer
plants.
question
From which phrase is the term "prions" derived?
answer
Proteinaceous infectious particles
question
In what year did Stanley Prusiner discover prions?
answer
1982
question
Which disease did Stanley Prusiner first identify as being caused by prions?
answer
Scrapie
question
How are prions different from other infectious agents?
answer
They lack nucleic acid.
question
The normal function of the PrP protein in mammals is believed to be
answer
assisting in normal synaptic development and function.
question
How do normal prion proteins (PrP) differ from the infectious prion proteins?
answer
Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
question
How does the number of infectious prions increase?
answer
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
question
Why are the beta-pleated multimers of PrP potentially pathogenic?
answer
The multimers are more stable and resistant to protease.
question
Which of the following prion diseases is found in deer and elk?
answer
Chronic wasting disease
question
Which of the following prion diseases was also known as laughing disease?
answer
Kuru
question
Which of the following conditions in humans is linked to bovine spongiform encephalopathy?
answer
Variant Creutzfeldt-Jakob disease
question
What part of the nervous system is most affected by fatal familial insomnia?
answer
Thalamus
question
Where does the name "scrapie" come from?
answer
The prion disorder causes infected sheep to scrape against objects until their skin is raw.
question
How are prions different from all other known infectious agents?
answer
They lack nucleic acid
question
Which of the following infectious particles do NOT have protein in their structure?
answer
viroids
question
Which of the following diseases is NOT caused by prions?
answer
Chagas' disease
question
Sort these pathogens based on the most useful/informative characteristics that would allow you to unambiguously identify the pathogen as a source of an infection.
answer
The following can be distinguished by their rRNA sequence: Mycobacterium tuberculosis, Coccidioides immitis, and Legionella pneumophila.
The following can be distinguished by their genome structure and composition: Influenza virus and Respiratory syncytial virus (RSV).
The following can be distinguished by their cell wall sructure: Mycobacterium tuberculosis and Coccidioides immitis.
The following can be identified using a Gram stain: Legionella pneumophila
question
Think about the many factors that are used to classify viruses. In order for Lauren to determine the type of virus she may have, she needs to understand some basic concepts about how viruses are characterized. Please sort the following statements as being true or false regarding characteristics of viruses.
answer
Correct Statement:
Viruses are not capable of metabolic activity on their own; they must have a host cell to reproduce.
The genetic material of a virus can be DNA or RNA.
Viruses can have different shapes.
Capsids function to surround and protect the nucleic acid core.
The genomes of viruses are usually smaller than the genomes of bacteria.
Incorrect Statement:
Capsids are acquired from the host cell during replication or release.
The intracellular state of a virus is called a virion.
All viruses have both a capsid and an envelope.
Haven't found what you need?
Search for quizzes and test answers now
Quizzes.studymoose.com uses cookies. By continuing you agree to our cookie policy
