Combo with "Mastering Microbiology Chapter 13" and 9 others

The host DNA integrates, with the prophage, into the new recipient chromosome
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?
During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
Which of the following is true concerning a lysogenic viral replication cycle?
To package and protect the viral genome
What is the function of the structural elements of a virus?
Their nucleic acids are injected into the cell.
How do naked viruses differ from enveloped viruses in their attachment/penetration phase?
+RNA viruses
Which virus employs the use of an RNA-dependent RNA polymerase?
Retroviruses
Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
Enveloped viruses
Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?
+RNA
Which of the following can be used directly as messenger RNA?
attachment
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing
release
Enveloped viruses have a layer of lipids surrounding their capsid. This envelope is made mostly of host cell membrane. In which step does the virus acquire this envelope?
the capsid breaks apart, releasing the viral genome
What occurs during viral uncoating?
Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host
Which of the following is true regarding cultivation and isolation of animal viruses?
Proteinaceous infectious particles
From which phrase is the term “prions” derived?
1982
In what year did Stanley Prusiner discover prions?
Scrapie
Which disease did Stanley Prusiner first identify as being caused by prions?
assisting in normal synaptic development and function.
The normal function of the PrP protein in mammals is believed to be:
Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
How do normal prion proteins (PrP) differ from the infectious prion proteins?
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion
How does the number of infectious prions increase?
The multimers are more stable and resistant to protease.
Why are the beta-pleated multimers of PrP potentially pathogenic?
shingles caused by the herpes zoster virus
Which of the following best describes Barbara’s condition?
1. virions attach to the host cells.
2. viral DNA is released into the nucleus of the host cell
3. enzymes required for multiplication of viral DNA are produced via transcription and translation
4. a copy of the DNA is made
5. capsid and other structural proteins are manufactured
6. virions are assembled to form complete viruses and are released from the host cell
What is the correct sequence of events for the replication of a DNA virus?
-her daughter and grandchildren moving into her house shortly after the death of her husband
-her age, 68
Which of the following factors could have contributed to Barbara’s development of shingles?
No. Because of their ages, the grandchildren have most likely been vaccinated against the chickenpox. They are also safe from contracting shingles because they are young.
Barbara is worried about spending time with her grandchildren while being treated for shingles. Can her grandchildren contract chickenpox or shingles from spending time with their grandmother?
cold sores or fever blisters
What disease does the human herpesvirus-1 cause?
-muscle pain
-headache
-fever
Which of the following are symptoms of influenza infection?
LEFT SIDE TOP TO BOTTOM:
-assists the virus in exiting the cell after reproduction
-protects the viral nucleic acid
-recognizes and attaches to host cells
-contains antigenic determinants

RIGHT SIDE:
-contains the viral genetic information

Drag each one of the labels onto the figure to identify the function of each structure.
1. hemagglutinin spikes attach to host cells
2. influenza enters the host cell
3. nucleic acid enters the host cytoplasm
4. influenza proteins are synthesized
5. influenza nucleic acid is packaged in a capsid
6. influenza particles bud from the cell, releasing the virus into the surrounding environment
Arrange the following statements in the order that best describes the sequence of events involved in the replication of influenza.
-little immunity to virus strains resulting from antigenic shift exists in the population.
-viral strains resulting from antigenic shift contain RNA segments from different species.
-antigenic shift results in a major change in the genetic composition of the virus
Which of the following statements regarding antigenic shift are true?
-increased fluid in the lungs and labored breathing
-an excessive inflammatory response leading to extensive tissue damage
Predict which of the following are reasonable outcomes of the cytokine storm during the 1918 flu pandemic.
-in order to yield a vaccine, the virus must be produced in eggs
-the virus undergoes antigenic changes on a regular basis
What are some of the current challenges to production of the influenza vaccine?
-an increase in the ability of the immune system to combat the infection
-overall decrease in the replication rate of influenza
-a decrease in the release of viral particles from the cell
Predict which of the following would be outcomes of treatment with Tamiflu.
penetration
In which stage is the viral DNA introduced into the cell?
Assembly
In which stage does formation of mature viruses occur?
The virus would not be able to infect new hosts
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
Attachment
Hint: Many of the proteins of the outside of a virus are used to identify and bind to a specific cell type.
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins of the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. What steps of viral replication are antibodies directly preventing?
The capsid breaks apart, releasing the viral genome
Hint: The goal of uncoating is to allow the virus’s genetic material to be accessed (and, therefore, replicated) by the host’s machinery
What occurs during vital uncoating?
The “host range” for a virus is determined by the presence or absence of particular components on the surface of the host cell that are required for the virus to attach.
Hint: Attachment of the virus to the host cell (the first step in the viral life cycle) requires binding of complementary molecules on the virus and host cell.
Which of the following statements concerning viruses is true?
Latent infections can persist for years in an individual without causing any symptoms
Which of the following statements regarding latent viral infections is true?
Retroviruses use an enzyme called revewse transcriptase, which synthesizes DNA by copying RNA.
Hint: Retroviruses have an RNA genome that is converted to DNA inside a host cell by viral reverse transcriptase
Which statement is CORRECT concerning animal viruses?
Spikes are found on some viruses. They are very consistent in structure and can be used for identification.
Hint: Some enveloped viruses have spikes, and they can be used for identification, such as the H and N spikes on the influenza virus
Which statement concerning viral structure is true?
During lysogeny, the viral genome intergrates into the host DNA, becoming a physical part of the chromosome.
Hint: It is inactive at this time, and virus is not produced.
Which of the following is true concerning a lysogenic viral replication cycle?
DNA polymerase
Which of the following is most likely a product of an early gene?
prion
An infectious protein is a?
cold sores
An example of a latent viral infection is?
latent viruses
Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called?
cause tumors to develop
Oncogenic viruses?
synthesis of – strand RNA
The following steps occur during biosynthesis of a + strand RNA virus. What is the third step?
synthesis of DNA
Which one of the following steps does NOT occur during multiplication of a picornavirus?
synthesis of double-stranded DNA
The following steps occur during multiplication of retroviruses. Which is the fourth step?
budding
The mechanism whereby an enveloped virus leaves a host cell is called?
injection of naked nucleic acid into the host cell
Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves?
2;3;4;1
Which of the following places these items in the correct order for DNA-virus replication?
1. Maturation
2. DNA synthesis
3. Transcription
4. Translation
uncoating
The following steps occur during multiplication of herpesviruses. Which of the third step?
biosynthesis
Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?
presence of receptor sites on the cell membrane
A virus ability to infect an animal cell depends primarily upon the?
B
In the figure, which structure is a complex virus
True
True or False
Helical and icosahedral are terms used to describe the shapes of a virus envelope?
They cannot reproduce themselves outside a host.
Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals?
Function of a viral structural elements.
Package and protect the viral genome
Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
Retrovirus
Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?
Enveloped viruses
Lysogenic viral DNA integrating into the host genome is referred to as
what?
Lysogeny
Which of the following events might trigger induction of a temperate bacteriophage?
Exposure to UV light
How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
The host cell dies during the lytic stage
What is the fate of the prophage during the lysogenic stage?
It is copied every time the host DNA replicates.
In which stage is the viral DNA introduced into the cell?
Prophage
In which stage does formation of mature viruses occur?
Assembly
The host DNA is usually degraged during which stage?
Synthesis
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
The virus would not be able to infect new hosts.
The following viral structures are in order from simplest to most complex.
Capsomere, Capsid, Nucleocapsid, Virion
Most viral genomes are much smaller than the genomes of the cells they infect. Which of the following CANNOT be inferred from this statement?
Most viruses can infect only certain types of cells.
The envelope found in some virus particles differs from the cytoplasmic membrane of cells in what way?
It does not perform the physiological functions carried out by the cytoplasmic membrane
What can assume one of three basic shapes?
Viral capsids
Some viruses have an outer membrane
Envelope
What is the first virus to be discovered and characterized?
Tobacco virus
Subunits that compose viral capsids
Capsomeres
20-sided polyhedral capsid
Icosahedron
How viruses are classified
Nucleic acid, presence of envelope, shape, size
Host specificity of a virus is due to what?
Interactions between viral and cellular surface molecules
Animal virus that does not have an envelope
Naked virion
Lipid membrane present in which type of organism?
Cells and viruses
Double-stranded DNA genomes are found in which type of organism?
In both cells and viruses
Double-stranded RNA genomes can be found in which type of organism?
Only in viruses
Cytoplasm is a characteristic of which type of organism?
Cells only
These are found in both cells and viruses.
Proteins
Infections with enveloped animal viruses are similar to lysogenic phage infections because
Infected cell may live for a long time
A phage T4 particle that has lost its tail fibers will have a replication cycle that is blocked at which of the following stages?
Attachment
A process in which viral capsids are removed within the infected cell.
Uncoating
Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?
Random collisions, chemical attractions, and receptor specificity
The phenomenon of transduction is associated with which of the stages of a bacteriophage infection cycle?
Assembly
Why is lysogeny advantageous to a bacteriophage?
The genetic material of the bacteriophage can be passed on to future generations of cells
Which of the following membranes can give rise to a viral envelope?
The nuclear and cytoplasmic membranes and the endoplasmic reticulum
How is the HIV provirus different from a lambda phage prophage?
The HIV provirus is integrated permanently into the host cell’s DNA
During ______, viruses remain dormant in a cell.
Latency
Virus replication results in the death of the cell in a(n) infection.
Lytic
A mechanism of release for enveloped viruses
Budding
Which of the following terms refers to a virus in the extracellular state?
Virion
The first virus to be identified was isolated from what type of organim?
Plant
The capsid of a virus is made out of which of the following types of molecules?
Protein
Basic types of viral shapes
Helical, polyhedral, complex
Why do viruses have to infect host cells?
They are dependent on host cell organelles and enzymes for their replication.
The ____ of a bacteriophage are most useful the attachment stage of the lytic replication cycle.
Tail Fibers
Which of the following is a major difference between a lysogenic and a lytic cycle in bacteriophages?
Viral DNA becomes a physical part of the bacterial chromosome only in a lysogenic cycle.
Bacteriophages can use all of the following structures for attachment to a bacterial cell
Pili, flagella, cell wall
What is the advantage of lysogeny to lambda phage
The phage persists for generations in the bacterial chromosome.
HeLa cells are an example of a _____ cell culture.
Continuous
Scientists have determined that prion diseases are not caused by a type of slow virus because prions
contain no nucleic acid
The assembly stage of the viral life cycle is usually a ______, although in some viruses it is controlled by enzymes
Spontaneous process
A prophage is excised from the host chromosome and viral replication proceeds in a process called _____.
Induction
Small, circular RNA molecules that are infectious to plants are called___
Viroids
An infection in which a host cell sheds new viruses slowly and steadily is called a(n) __________ infection.
Persistent
A technique used to estimate the numbers of bacteriophages in a culture is called a(n) __________ assay.
Plaque
As a group, prion diseases are more formally known as ______.
Spongiform Encephalopathies
an infectious particle of protein and nucleic acid outside a host cell
an accurate description of a virion?
both protection and recognition
The outermost layer of a virion fulfills which of the following functions of the virus?
bacteriophage
A ________ is a virus that infects bacterial cells.
interactions between viral and cellular surface molecules.
Host specificity of a virus is due to
capsid
The shape of a virion is a function of the ________ of the virus.
host cell membranes containing virus-encoded glycoproteins.
The envelope portion of an enveloped virus is composed of
orders and families
Classification of viruses includes
III, V, I, II, IV
What is the correct order for the stages of a lytic replication cycle, from earliest to latest stages?
I. Synthesis
II. Assembly
III. Attachment
IV. Release
V. Entry
both endocytosis and direct penetration.
Naked capsid animal viruses gain entry to host cells by
digestion of host DNA
Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but not in the lysogenic cycle?
lysogenic
Zones of clearing in cell cultures that are the result of virus infection are called plaques. Sometimes “cloudy plaques” are seen on bacterial cultures infected with bacteriophage. What type of viral infection might cause this appearance?
HIV; membrane fusion
Which virus is CORRECTLY matched with its method of entry?
reverse transcriptase
Retroviruses require the activity of ________ to complete their infection cycle.
the nuclear and cytoplasmic membranes, and the endoplasmic reticulum
Which of the following membranes can give rise to a viral envelope?
malignant tumors.
The process of metastasis results from
a series of separate events over time lead to the loss of cell cycle regulation.
The development of a cancerous cell is said to require “multiple hits.” This means
determining the density of phage in a culture.
Plaque assays are used for
The use of animals is expensive, and unethical to many people.
What is one of the most difficult aspects of studying animal viruses?
naked viruses
Infection with ________ is likely to result in destruction of the host cell by lysis.
they only grow in normal human cells.
Some human viruses are difficult to study because
possession of a genome that directs synthesis of materials necessary for replication
Which of the following is a feature shared by viruses and living organisms?
viroids.
Small circular RNA molecules without capsids are characteristic of
mammals.
Prions cause disease in
tumor
A ________ is a mass of neoplastic cells.
budding
The process known as ________ is a mechanism of release for enveloped viruses.
false
Viruses cause most human cancers.
true
Virus entry requires the presence of specific cell structures.
true
Protozoa are susceptible to viral attack.
true
All members of a virus family have the same type of genome structure.
false
Bacteriophage release is a gradual process in which small numbers are released at a time.
true
Fertilized chicken eggs are used to culture some vaccine strains
nucleocaspid
The combination of a virus’s protein coat and nucleic acid core is called the ________
helical
The first virus isolated, Tobacco mosaic virus, has a ________ capsid morphology, which facilitated its isolation.
continuous
Some viruses can be cultured on ________ cells which are descended from neoplastic cells.
uncoating
The process in which viral capsids are removed within the infected cell is called ________
protooncongenes
Genes that play a role in proper cell division but may also play a role in some types of cancer are called ________
plaque
A ________ is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.
Compare and contrast the ways in which animal, plant, and bacterial viruses gain entry into their host cells.
Nucleic acid core-DNA, RNA
Capsid-surrounding protein coat
Envelope-some virus-surrounding lipid bilayer membrane
Spike-surface projections, glyproteins, attach to the host cells
lysogenic replication cycle
Viruses lack cytoplasm and organelles
In what ways do viruses differ from other pathogens?
both protection and recognition
The outermost layer of a virion fulfills which of the following functions of the virus?
bacteriophage
A(n) ________ is a virus that infects bacterial cells.
type of nucleic acid
Which of the following is a characteristic by which viruses are classified?
the capsid
Which of the following is primarily responsible for the shape of a virion?
They have no extracellular state
How are fungal viruses different from viruses that infect other organisms?
viroids
Which of the following infectious particles do NOT have protein in their structure?
The inserted viral DNA may leave the host DNA.
Which of the following may occur in a lysogenic infection, but not a latent one
Some virus family names are derived from the name of an important member of the family.
Which of the following statements regarding virus taxonomy is true?
Genus and specific epithet are used in both classification systems
Which of the following statements comparing virus classification and taxonomy of organisms is true?
III, V, I, II, IV
Which of the following places stages of a lytic replication cycle in order, from earliest to latest stages?
random collisions, chemical attractions, and receptor specificity
Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?
entry and release
The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle?
direct penetration
Which means of entry into host cells is common to both some animal viruses and bacteriophage T4?
digestion of host DNA
Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but NOT in the lysogenic cycle?
The genetic material of the bacteriophage is amplified many times over that seen in a lytic phage.
Why is lysogeny advantageous to a bacteriophage?
both UV light and X-rays
Which of the following agents is capable of inducing conversion of a prophage to the lytic cycle
lysogenic
Zones of clearing in cell cultures that are the result of virus infection are called plaques. Sometimes “cloudy plaques” are seen on bacterial cultures infected with bacteriophage. What type of viral infection might cause this appearance?
adenovirus; membrane fusion
Which of the following is matched INCORRECTLY?
retroviruses
Reverse transcriptase is associated with which of the following?
+ssRNA viruses
The genome of which of the following types of animal virus can act directly as mRNA?
-ssRNA viruses
Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated?
a DNA polymerase.
In contrast to most dsDNA animal viruses, the poxviruses replicate solely in the cytoplasm of the host cell. This fact implies that the viral genome may encode
the nuclear and cytoplasmic membranes and the endoplasmic reticulum
Which of the following membranes can give rise to a viral envelope?
neoplasia
A cell is infected with a virus carrying an oncogene sequence in its genome. What process may occur if the oncogene is expressed in the infected cell?
The HIV provirus is integrated permanently into the host cell’s DNA
How is the HIV provirus different from a lambda-phage prophage?
both cell cultures and embryonated eggs
Which of the following laboratory procedures is used for culturing animal viruses in the laboratory?
retroviruses
One mechanism by which viruses may cause cancer is to interrupt the genetic regulatory sequences of repressor proteins. Which of the following types of viruses is most likely to be involved in causing cancer by this mechanism?
metastasis
Tumors invade other organs and tissues in a process called
determine the density of phage in a culture
Plaque assays are used for
both longevity and source of cells
Diploid cell cultures and continuous cell cultures differ in which of the following ways?
plants
Viroids infect
prions
The viruses of fungi have RNA genomes and lack a capsid. They are therefore similar to
enveloped viruses
A lipid membrane is present in which of the following?
they only grow in normal human cells.
Some human viruses are difficult to study because
only in viruses
Double-stranded RNA genomes can be found
possession of a genome that directs synthesis of materials necessary for replication
Which of the following is a feature shared by viruses and living organisms?
viroids
Small circular RNA molecules without capsids are characteristic of
lysogenic infection.
Viruses are shed slowly and steadily during
latency
During ________, viruses remain dormant in animal cells.
a lytic
Virus replication results in the death of the cell in ________ infection(s).
tumor
A ________ is a mass of neoplastic cells.
budding
The process known as ________ is a mechanism of release for enveloped viruses
false
Viruses cause most human cancers.
true
Most viruses cannot be seen by light microscopy
true
Protozoa are susceptible to viral attack.
true
Many diseases of plants are caused by infectious RNA molecules lacking capsids
false
Assembly of new viruses is a process that usually requires the direction of a variety of viral and cellular enzymes.
true
Bovine spongiform encephalopathy is an example of a prion disease.
false
All viruses use the host cell’s nucleic acid polymerases for replication
nucleocapsid
The combination of a virus’s protein coat and nucleic acid core is called the (capsid/virion/nucleocapsid).
capsomeres
Viral capsids are composed of subunits called (nucleocapsids/capsomeres).
affinity
Virus infection is initiated by the specific (fit/affinity/interaction) between proteins on the surface of a virion the surface of the target cell.
continuous
Some viruses can be cultured on (continuous/diploid/animal) cells which are descended from neoplastic cells.
complex
The virions shown in the figure have a (polyhedral/helical/complex) capsid.
temperate
Another term for a lysogenic phage is a (temperate/latent/prophage) phage
uncoating
The process in which viral capsids are removed within the infected cell is called (entry/disassembly/uncoating)
neoplasia
Uncontrolled cell division in animals is known as (metastasis/neoplasia/cancer).
transcriptase
RNA viruses such as HIV require the activity of reverse (transcriptase/polymerase) to become proviruses.
matrix
In enveloped viruses, virus-encoded (matrix/capsomeres/envelope) proteins are required for the assembly of the envelope around the capsid.
plaque
A (colony/plaque) is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.
orders
Three (orders/families/classes) represent the highest level of taxonomic rank used in classifying viruses.
PrP
Prions are composed of a single protein called (plaque/BSE/PrP).
naked
An animal virus that does not have an envelope is described as a(n) (naked/unenveloped/capsid) virion
The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
How does specialized transduction differ from regular lysogeny?
The host DNA integrates, with the prophage, into the new recipient chromosome
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?
The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?
During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
Which of the following is true concerning a lysogenic viral replication cycle?
They require a host in order to reproduce.
How are viruses different from cells?

They require a host in order to reproduce.
They do not contain genetic material.
They do not contain enzymes.
They do not contain protein.

To package and protect the viral genome
What is the function of the structural elements of a virus?

To provide a source of energy for the virus
To use all of the cell proteins
To package and protect the viral genome

a prophage
Lysogenic viral DNA integrating into the host genome is referred to as

a prophage.
induction.
lytic.
lysogeny.

Exposure to UV light
Which of the following events might trigger induction of a temperate bacteriophage?

An infected cell entering the logarithmic phase of growth
Bacterial conjugation
Normal cell division of an infected cell
Exposure to UV light

It is copied every time the host DNA replicates.
What is the fate of the prophage during the lysogenic stage?

It is packaged into viral proteins and maintained until the host is exposed to an environmental stress.
It is degraded by the activity of host defense enzymes.
It is released from the cell by lysing the cell.
It is copied every time the host DNA replicates.

+RNA viruses
Which virus employs the use of an RNA-dependent RNA polymerase?
Retroviruses
Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
Enveloped viruses
Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?
+RNA
Which of the following can be used directly as messenger RNA?
attachment
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing
the capsid breaks apart, releasing the viral genome
What occurs during viral uncoating?
Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host
Which of the following is true regarding cultivation and isolation of animal viruses?
Scrapie
Which disease did Stanley Prusiner first identify as being caused by prions?
assisting in normal synaptic development and function.
The normal function of the PrP protein in mammals is believed to be:
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion
How does the number of infectious prions increase?
The multimers are more stable and resistant to protease.
Why are the beta-pleated multimers of PrP potentially pathogenic?
cold sores or fever blisters

Correct
Correct! Cold sores or fever blisters are the painful, short-lived vesicles that form near the outer margins of the lips. It is transmitted via oral and respiratory routes. In the United States, a large percentage of the population is infected with this virus during infancy, when the virus is passed via respiratory droplets from family members. (Who can resist kissing a baby?)

What disease does the human herpesvirus-1 cause?

canker sores
chancres
cold sores or fever blisters
infectious mononucleosis

1. virions attach to the host cells.
2. viral DNA is released into the nucleus of the host cell
3. enzymes required for multiplication of viral DNA are produced via transcription and translation
4. a copy of the DNA is made
5. capsid and other structural proteins are manufactured
6. virions are assembled to form complete viruses and are released from the host cell

Correct! Viruses depend on host cells for replication. The herpes zoster virus is a DNA virus. It enters the host cell by attaching to host cell receptors. Once inside, the virion is uncoated to release the DNA into the nucleus of the host cell. “Early” genes, typically used for viral replication, are transcribed using the host’s RNA polymerase. Viral DNA is then replicated to produce multiple copies of the DNA. The remaining components of a virion are the produced via transcription and translation of “late” genes. Capsid proteins then migrate to the nucleus of the host cell. Maturation occurs when the capsid proteins and viral DNA combine to form a complete virus. The virions are then released from the host cell to go and infect new host cells. Image C diagrams the replication of papovavirus, a DNA virus similar to herpesvirus.

What is the correct sequence of events for the replication of a DNA virus?
Arrange the following statements in chronological order .
-her daughter and grandchildren moving into her house shortly after the death of her husband
-her age, 68

Many factors can contribute to reactivation of a latent virus. Research has yet to narrow it down to one thing, but stress, old age, and a change in the host’s immune system have been linked to viral reactivation.

Which of the following factors could have contributed to Barbara’s development of shingles?

her daughter and grandchildren moving into her house shortly after the death of her husband
the vaccinations that Barbara received as a child
her age, 68
a new exposure to the varicella virus

-muscle pain
-headache
-fever
Which of the following are symptoms of influenza infection?
-little immunity to virus strains resulting from antigenic shift exists in the population.
-viral strains resulting from antigenic shift contain RNA segments from different species.
-antigenic shift results in a major change in the genetic composition of the virus
Which of the following statements regarding antigenic shift are true?
-increased fluid in the lungs and labored breathing
-an excessive inflammatory response leading to extensive tissue damage
Predict which of the following are reasonable outcomes of the cytokine storm during the 1918 flu pandemic.
-in order to yield a vaccine, the virus must be produced in eggs
-the virus undergoes antigenic changes on a regular basis
What are some of the current challenges to production of the influenza vaccine?
-an increase in the ability of the immune system to combat the infection
-overall decrease in the replication rate of influenza
-a decrease in the release of viral particles from the cell
Predict which of the following would be outcomes of treatment with Tamiflu.
penetration
In which stage is the viral DNA introduced into the cell?
Assembly
In which stage does formation of mature viruses occur?
The virus would not be able to infect new hosts
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
Scrapie
Which disease did Stanley Prusiner first identify as being caused by prions?
Assisting in normal synaptic development and function
The normal function of the PrP protein in mammals is believed to be:
The multimers are more stable and resistant to protease.
Why are the beta-pleated multimers of PrP potentially pathogenic?
Chronic wasting disease
Which of the following prion diseases is found in deer and elk?
Kuru
Which of the following prion diseases was also known as laughing disease?
Variant Creutzfeldt-Jakob disease
Which of the following conditions in humans is linked to bovine spongiform encephalopathy?
Thalamus
What part of the nervous system is most affected by fatal familial insomnia?
The prion disorder causes infected sheep to scrape against objects until their skin is raw
Where does the name “scrapie” come from?
Chagas’ disease
Which of the following diseases is NOT caused by prions?
Prion

Prion diseases in a wide number of species are associated with spongiform changes in brain tissue

A 32 year old father of two small children lived in the Midwestern United States. An avid hunter since childhood, the man visited annually with family and friends in Colorado for elk hunting. His job required frequent travel to Europe, where he enjoyed exotic foods.

In 1988, his wife recalls, he began having problems. Frequently he forgot to pick up things from the store or even that his wife had called him. Later that year, he was unable to complete paperwork at his business and had difficulty performing even basic math. In England on business, he had forgotten his home phone number in the United States and couldn’t remember how to spell his name for directory assistance.

By September, his wife insisted he seek medical care. All the standard blood tests came back normal. A psychologist diagnosed depression, but a brain scan revealed spongiform changes. He was given six weeks to live because there is no treatment for this disease.

What is the most likely etiology (cause) of this disease?

He is likely to have been exposed while hunting elk in Colorado during his childhood

Elk are part of the family of Cervidae that have been shown to carry prions

How did this man most likely become exposed to this disease agent?
No, the disease is not contagious

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

Is this disease contagious?
Brain scan

The spongiform lesions noted on the brain scan are characteristic of prion diseases.

Which test confirmed the presence of this prion disease?
Decades

Prion diseases are usually apparent decades after the initial exposure.

What is the typical incubation period for prion disease?
Ocular herpes- eyes
Fever blisters- around the mouth
Genital herpes- penis
Whitlow- fingers
Label the lesions of the human herpesvirus that occur at various locations on the human body.
Papillomavirus

Papillomaviruses can produce warts in susceptible hosts

Ten year old Rudy has several large warts on the fingers of his right hand. They do not hurt, but their unsightly appearance causes him to shy away from people. He is afraid to shake hands, or to play with other children out of fear that he may transfer the warts to them. Initially, his mother tells him not to worry about them, but Rudy cannot help feeling self-conscious. Furthermore, Rudy fears that the warts may somehow spread on his own body. After consulting with a physician, his mother decides to have the warts surgically removed.

What causes warts?

Yes. Papillomaviruses are spread by direct contact.

This is called autoinoculation.

Is it possible for Rudy’s warts to spread to other areas of his body?
cancer of the tonsils

Papillomavirus infections increase the risk of cancer in the tonsils fourteenfold

What type of cancer is more likely to develop in people who have had papillomavirus infections?
Are: daily application of salicylic acid, covering the wart with a piece of duct tape for several weeks, “freezing” the wart with liquid nitrogen

Warts are caused by viruses. Daily application of tincture of iodine would be unlikely to have any effect on the wart.

Which of the following is NOT an accepted treatment for warts?
Varicella-zoster virus

The varicella-zoster virus is the cause of both chicken pox in the young and shingles in the elderly (people who recovered from chicken pox decades earlier)

The Davises were excited about their newborn twin boys and couldn’t wait to take them to see Mr. Davis’s father. Grandfather Davis was excited to see his first grandsons as well and thought their first visit might take his mind off the pain of his shingles, which has suddenly appeared only days before.

Which virus is responsible for Grandfather Davis’s shingles?

dsDNA

The varicella-zoster virus contains dsDNA

Which nucleic acid is part of the varicella-zoster viron?
Yes. The twins would probably develop chicken pox two weeks after their visit with Grandfather Davis.

The virus shed from the grandfather’s shingles lesions would produce chicken pox lesions in the children.

Is Grandfather Davis contagious?
12 months of age

Children usually receive their chicken pox vaccine at 12-15 months of age

What is the recommended schedule for the first chicken pox vaccine in infants?
Attenuated virus vaccine

The vaccine for chicken pox contains an attenuated virus

What type of vaccine would be used to vaccinate the twins?
A person can get shingles from a person who has chickenpox
All of these statements are characteristics of VZV infections EXCEPT ____.
The location of the wart
In what way does a seed wart differ from a flat wart?
chickenpox
Shingles, or herpes zoster, is a reactivation of the virus that causes
papillomaviruses
Common skin warts are the result of infection with
Integrate into the host cell DNA
Some strains of Papillomavirus are oncogenic due to their ability to
chickenpox
The rash described as “teardrops on rose petals” is characteristic of
shingles
Chickenpox and (herpes/shingles/warts) are caused by the same virus
shingles
Localization of lesions within a band of skin on one side of the body is a characteristic of the disease (measles/shingles/sporotrichosis)
plantar
Warts on the sole of the foot are known as (seed/flat/plantar) warts
Candida albicans

Diagnosis of a yeast infection usually involves patient history, observation of yeast cells via microscopy, and growth of a culture on Sabouraud dextrose agar. Differentiation between yeasts and bacteria is reliant on biochemical characteristics. Differentiation between yeasts and molds is reliant on spore type and function.

Tori, a 24 year old graduate student, had been suffering from a respiratory infection for over a week. She went to the student health center, where the physician prescribed her a brad spectrum antibiotic. By he end of her round of antibiotics, Tori was no longer suffering from respiratory complications, but she had noticed an increase in itchiness in her genital region. Within a few days, the itchiness was getting worse and was accompanied by a vaginal discharge that had a cheesy consistency and foul odor. Tori returned to the student health center to discuss her condition with the physician. A sample of her discharge was taken and sent to the laboratory for microscopy and plating.

Based on the lab results, which organism is most likely causing Tori’s new symptoms?

The antibiotics that treated Tori’s primary respiratory infection also removed some of her normal bacterial flora, resulting in an overgrowth of other organisms.
Which of the following best explains why Tori developed a new series of symptoms?
Oral thrush and fulminating disease
The laboratory confirmed that the causative agent of Tori’s infection was Candida albicans, a yeastlike fungus. The doctor prescribed her a single dose of fluconazole and told her to purchase an over the counter cream containing miconazole for any recurrent vaginal symptoms.

Which of the following are also caused by C. albicans?

Fungal cells and human cells have a nucleus, multiple organelles, and 80S ribosomes for protein synthesis
Which of the following statements best describes why the treatment for Tori’s fungal infection may result in side effects to her own cells?
Blastoconidia and chlamydoconidia are spore structures produced by budding in yeasts, whereas bacterial endospores are produced by bacteria under extreme conditions
How do blastoconidia and chlamydoconidia produced by yeast differ from bacterial endospores?
Yeasts us pseudohyphae to invade host tissue, whereas filamentous fungi use their vegetative hyphae for obtaining nutrients
How do pseudohyphae in yeasts differ from vegetative hyphae in filamentous fungi?
Trichophyton species
Which of the following could cause athlete’s foot?
dermatophytes growing in the upper dead tissue layers of the skin
“Ringworm” is caused by
chromoblasomycosis
A man is suffering severe foot pain in the area of what looks like a large wart. He reports he has had the wart for some time, and the pain and swelling have developed slowly. A sample from the lesion shows that the pus contains large cells that stain a golden brown color. The man is likely suffering from
False
Because they are common soil saprobes, dermatophytes are fungi that are not contagious in humans
False
Chromoblastomycosis is rarely a sever disease and can be treated easily with appropriate drugs.
scrapie
Which disease did Stanley Prusiner first identify as being caused by prions?
prophage
Lysogenic viral DNA integrating into the host genome is referred to as
Exposure to UV light
Which of the following events might trigger induction of a temperate bacteriophage?

ANSWER:
1) Normal cell division of an infected cell
2) Bacterial conjugation
3) An infected cell entering the logarithmic phase of growth
4) Exposure to UV light

It is copied every time the host DNA replicates.
What is the fate of the prophage during the lysogenic stage?

1) It is packaged into viral proteins and maintained until the host is exposed to an environmental stress.
2) It is copied every time the host DNA replicates.
3) It is degraded by the activity of host defense enzymes.
4) It is released from the cell by lysing the cell.

+RNA viruses
Which virus employs the use of an RNA-dependent RNA polymerase?
retroviruses
Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
enveloped viruses
Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?

+RNA viruses
dsRNA viruses
Naked viruses
Enveloped viruses

+RNA
Which of the following can be used directly as messenger RNA?

+RNA
-RNA
ssDNA

Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).
Which of the following statements concerning prion diseases is true?

Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).
Prion diseases are always inherited.
Prion diseases affect humans but not other animals.
Prion diseases affect brain function but do not affect the morphology (overall appearance) of brain tissues.

The “host range” for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.
Which of the following statements concerning viruses is true?

Viruses contain both DNA and RNA, and they undergo binary fusion.
Viruses possess enzymes for protein synthesis and ATP generation.
The “host range” for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.
Viruses are usually about the same size as bacteria.

penetration
In which stage is the viral DNA introduced into the cell?
assembly/maturation
In which stage does formation of mature viruses occur?
The virus would not be able to infect new hosts.
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?

The virus would infect new hosts.
The virus would not be able to infect new hosts.
The cell could still be revived by the virus.

Creutzfeldt-Jakob disease (CJD)
Name the human disease caused by prions?
attachment
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing?
The capsid breaks apart, releasing the viral genome.
What occurs during viral uncoating?
Latent infections can persist for years in an individual without causing any symptoms.
Which of the following statements regarding latent viral infections is true?

During latent infections, small amounts of virus are produced, and virus numbers build up over time.
Latent infections can persist for years in an individual without causing any symptoms.
Latent viral infections are caused by the slow conversion of cellular glycoproteins from normal to infectious form.
Latent viral infections are almost always fatal.

Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA.
Which statement is CORRECT concerning animal viruses?

The genome of animal viruses is always single-stranded.
Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA.
Capsid proteins are produced in the nucleus.
Enveloped viruses are surrounded by a lipid and carbohydrate coat, which is made from the host cell’s mitochondria.

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
Which of the following is true concerning a lysogenic viral replication cycle?
ANSWER:
Lysogenic infections are similar to persistent infections, in that virus is constantly produced.
During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
During lysogeny, the viral DNA is present as a circular plasmid.
Once the lysogenic portion of the cycle has begun, virus is never produced again.
coronavirus
Which virus is NOT associated with cancer?
ANSWER:
Epstein-Barr virus (EBV)
coronavirus
human papillomavirus (HPV)
hepatitis B virus (HBV)
assisting in normal synaptic development and function.
The normal function of the PrP protein in mammals is believed to be:
The multimers are more stable and resistant to protease.
Why are the beta-pleated multimers of PrP potentially pathog
It infects many kinds of cells in many different hosts
Which of the following statements describes a generalist virus?
1. attachment
*2. ENTRY
3. bacterial chromosome degraded
4. synthesis
5. assembly
6. release
All of these are steps in the lytic cycle of a temperate bacteriophage. Which happens second?
1. order
2. family
3. genus
4. specific epithet
*class is NOT
Which of the following is NOT represented in viral classification schemes?
1. Bovine Spongiform Encephalitis
2. Kuru
3. Scrapie
*Chagas’ disease is NOT
Which of the following diseases is NOT caused by prions?
Entry and Release
Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4?
it does not perform the physiological functions carried out by the cytoplasmic membrane (such as endocytosis or active transport)
The envelope found in some virus particles differs from the cytoplasmic membrane of cells in that __________.
a. ribosomes
*b. capsid- all viruses have a capsid surrounding their nucleic acid
c. envelope
d. DNA
Which of the following is an essential component of all viruses?
viral DNA becoming imbedded within the host cell’s chromosomes.
Lysogeny refers to…?
Animal viruses do not undergo lysogeny.
Lysogeny is associated with all of the following EXCEPT…
a. bacteriophages
b. animal viruses
c. increasing virulence of host bacterium
d. a prophage
capsomere
capsid
nucleocapsid
virion
Put the following viral structures in order, from simplest to most complex: I. virion II. capsomere III. capsid IV. nucleocapsid
sterile nutrient agar- Viruses cannot be grown in sterile nutrient agar or other microbiological media because viruses must have a host cell present to reproduce.
Viruses can be grown in all of the following EXCEPT __________.
a. embryonated eggs
b. tissue culture
c. sterile nutrient agar
d. live animals
The phage is in the lysogenic cycle
You have isolated bacterium that contains a prophage. Which of the following is true concerning the prophage?
20. Each plaque on the plate corresponds to a single phage.
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?
inactivation of an oncogene
Which of the following would be an appropriate mode of action for a new anticancer drug?
cellular DNA polymerase. Most dsDNA viruses do not require any kind of special enzyme for their replication because they are able to utilize the normal enzymes and processes of the host cell.
Which of the following types of enzymes is necessary for the replication of most double-stranded DNA (dsDNA) viruses?
b. Most viruses can infect only certain types of cells.
Most viral genomes are much smaller than the genomes of the cells they infect. Which of the following CANNOT be inferred from this statement?
a. Viral genomes can be enclosed in very small capsids.
b. Most viruses can infect only certain types of cells.
c. Viral genomes usually contain fewer genes than cellular genomes.
d. Viral genomes usually do not encode all of the enzymes or structures necessary for their replication.
b. they live inside host cells
Which of the following is NOT a way in which viruses differ from all other living things?
a. they cannot self replicate
b. they live inside host cells
c. they cannot respond to environmental stimuli through metabolic changes
d. they do not grow
attachment
A phage T4 particle that has lost its tail fibers will have a replication cycle that is blocked at which of the following stages?
a. entry
b. synthesis
c. attachment
d. assembly
disruption of cell division
Both viruses and carcinogenic chemicals can cause tumors by __________.

a. killing cells
b. disruption of cell division
c. creating new cellular genes
d. slowing cellular growth

a random collision
Contact between a phage and its bacterial host occurs by _____.
Only the T4 genome enters the bacterial cell.
What portion of bacteriophage T4 enters E. coli?
Only the T4 genome enters the bacterial cell.
Once entry into the bacterial cell has been achieved, the next step in a lytic replication cycle is _____.
Phage enzymes degrade the bacterial DNA.
During a lytic replication cycle, what action does a phage take to ensure that its host bacterium does NOT continue synthesizing cellular molecules?
the bacterial cell bursting open
In a lytic cycle of replication, release of phages involves _____.
the phage genome inserts itself into the host genome
A major difference between the lytic and lysogenic cycles of phage replication is that during the lysogenic phase _____.
UV light
What factor may induce a prophage to enter the lytic cycle?
lysogenic conversion
During the lysogenic cycle, it is possible for integrated phage genes to change the characteristics of the host cell. This is known as _____.
to package and protect the viral genome
What is the function of the structural elements of a virus?
a prophage
Lysogenic viral DNA integrating into the host genome is referred to as
exposure to UV light
Which of the following events might trigger induction of a temperate bacteriophage?
it is copied every time the host DNA replicates
What is the fate of the prophage during the lysogenic stage?
attachment
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing?
the capsid breaks apart
What occurs during viral uncoating?
assisting the normal synaptic development and function
The normal function of the PrP protein in mammals is believed to be:
The multimers are more stable and resistant to protease
Why are the beta-pleated multimers of PrP potentially pathogenic?
the infected cell may live for a long time. Because enveloped viruses are shed slowly and persistently from the host cell by budding, the host cell may survive for a long time.
The infectious cycles of enveloped animal viruses and temperate bacteriophages are most similar because __________.
d) assisting in normal synaptic development and function
Part A
The normal function of the PrP protein in mammals is believed to be:
a) assisting proteins in forming beta-pleated sheets.
b) assisting proteins in forming alpha-helices.
c) assisting in normal membrane development and function.
d) assisting in normal synaptic development and function
d) The multimers are more stable and resistant to protease
Part D
Why are the beta-pleated multimers of PrP potentially pathogenic?
a) They are not detected by other organisms.
b) They are found on the surface of immune cells, resulting in damage to the immune system.
c) They repress the immune system.
d) The multimers are more stable and resistant to protease
d) It infects many kinds of cells in many different hosts
Which of the following statements describes a generalist virus?
a) It can have several different types of genomes.
b) It does not cause disease in the organisms it infects.
c) It does not have a particular sequence of events in its life cycle.
d) It infects many kinds of cells in many different hosts
b) have no extracellular state
Fungal viruses
a) are the most numerous type of virus.
b) have no extracellular state.
c) infect many food crops.
d) have been extensively studied
d) they do not contain nucleic acids.
Conventional genetic analyses of prions involving rRNA sequences are impossible because
a) they are too small to be analyzed genetically.
b) they cannot be isolated in a pure form.
c) they do not contain rRNA.
d) they do not contain nucleic acids.
a) cellular DNA polymerase
Which of the following types of enzymes is necessary for the replication of most double-stranded DNA (dsDNA) viruses?
a) cellular DNA polymerase
b) RNA-dependent RNA transcriptase
c) viral RNA polymerase
d) reverse transcriptase
b) attachment
A phage T4 particle that has lost its tail fibers will have a replication cycle that is blocked at which of the following stages?
a) assembly
b) attachment
c) entry
d) synthesis
d) synthesis
Which of the following is the midpoint of a lytic replication cycle?
a) release
b) attachment
c) entry
d) synthesis
a) different strains have various kinds of genetic abnormalities
HeLa cells are regarded as a semistandard human tissue culture medium because
a) different strains have various kinds of genetic abnormalities.
b) they divide only a limited number of times before they die.
c) they are contaminated with egg proteins.
d) they are infected with contaminating bacteria
b) attachment
Part A
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing?
a) uncoating
b) attachment
c) assembly
d) synthesis
a) The capsid breaks apart, releasing the viral genome
Part C
What occurs during viral uncoating?
a) The capsid breaks apart, releasing the viral genome.
b) The nucleic acid breaks apart, allowing for translation.
c) The viral envelope is released.
d) The viral proteins are synthesized
c) Scrapie
Part C
Which disease did Stanley Prusiner first identify as being caused by prions?
a) Fatal familial insomnia
b) Kuru
c) Scrapie
d) Mad cow disease
d) They require a host in order to reproduce
Part A
How are viruses different from cells?
a) They do not contain genetic material.
b) They do not contain enzymes.
c) They do not contain protein.
d) They require a host in order to reproduce.
a) To package and protect the viral genome
Part B
What is the function of the structural elements of a virus?
a) To package and protect the viral genome
b) To provide a source of energy for the virus
c) To use all of the cell proteins
a) class
Which of the following is NOT represented in viral classification schemes?
a) class
b) genus
c) family
d) specific epithet
c) entry and release
Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4?
a) assembly
b) entry
c) entry and release
d) attachment
c) 20
In a plaque assay, a microbiologist counts 20 plaques on a plate. How many phage particles 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?
a) 40
b) 10
c) 20
d) 2

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