question

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?

answer

The host DNA integrates, with the prophage, into the new recipient chromosome

question

Which of the following is true concerning a lysogenic viral replication cycle?

answer

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

question

What is the function of the structural elements of a virus?

answer

To package and protect the viral genome

question

How do naked viruses differ from enveloped viruses in their attachment/penetration phase?

answer

Their nucleic acids are injected into the cell.

question

Which virus employs the use of an RNA-dependent RNA polymerase?

answer

+RNA viruses

question

Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?

answer

Retroviruses

question

Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?

answer

Enveloped viruses

question

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

answer

+RNA

question

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

answer

attachment

question

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?

answer

release

question

What occurs during viral uncoating?

answer

the capsid breaks apart, releasing the viral genome

question

Which of the following is true regarding cultivation and isolation of animal viruses?

answer

Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host

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

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 best describes Barbara's condition?

answer

shingles caused by the herpes zoster virus

question

What is the correct sequence of events for the replication of a DNA virus?

answer

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

question

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

answer

-her daughter and grandchildren moving into her house shortly after the death of her husband -her age, 68

question

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?

answer

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.

question

What disease does the human herpesvirus-1 cause?

answer

cold sores or fever blisters

question

Which of the following are symptoms of influenza infection?

answer

-muscle pain -headache -fever

question

Drag each one of the labels onto the figure to identify the function of each structure.

answer

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

question

Arrange the following statements in the order that best describes the sequence of events involved in the replication of influenza.

answer

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

question

Which of the following statements regarding antigenic shift are true?

answer

-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

question

Predict which of the following are reasonable outcomes of the cytokine storm during the 1918 flu pandemic.

answer

-increased fluid in the lungs and labored breathing -an excessive inflammatory response leading to extensive tissue damage

question

What are some of the current challenges to production of the influenza vaccine?

answer

-in order to yield a vaccine, the virus must be produced in eggs -the virus undergoes antigenic changes on a regular basis

question

Predict which of the following would be outcomes of treatment with Tamiflu.

answer

-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

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

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

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?

answer

Attachment Hint: Many of the proteins of the outside of a virus are used to identify and bind to a specific cell type.

question

What occurs during vital uncoating?

answer

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

question

Which of the following statements concerning viruses is true?

answer

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.

question

Which of the following statements regarding latent viral infections is true?

answer

Latent infections can persist for years in an individual without causing any symptoms

question

Which statement is CORRECT concerning animal viruses?

answer

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

question

Which statement concerning viral structure is true?

answer

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

question

Which of the following is true concerning a lysogenic viral replication cycle?

answer

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.

question

Which of the following is most likely a product of an early gene?

answer

DNA polymerase

question

An infectious protein is a?

answer

prion

question

An example of a latent viral infection is?

answer

cold sores

question

Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called?

answer

latent viruses

question

Oncogenic viruses?

answer

cause tumors to develop

question

The following steps occur during biosynthesis of a + strand RNA virus. What is the third step?

answer

synthesis of - strand RNA

question

Which one of the following steps does NOT occur during multiplication of a picornavirus?

answer

synthesis of DNA

question

The following steps occur during multiplication of retroviruses. Which is the fourth step?

answer

synthesis of double-stranded DNA

question

The mechanism whereby an enveloped virus leaves a host cell is called?

answer

budding

question

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves?

answer

injection of naked nucleic acid into the host cell

question

Which of the following places these items in the correct order for DNA-virus replication? 1. Maturation 2. DNA synthesis 3. Transcription 4. Translation

answer

2;3;4;1

question

The following steps occur during multiplication of herpesviruses. Which of the third step?

answer

uncoating

question

Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?

answer

biosynthesis

question

A virus ability to infect an animal cell depends primarily upon the?

answer

presence of receptor sites on the cell membrane

question

In the figure, which structure is a complex virus

answer

B

question

True or False Helical and icosahedral are terms used to describe the shapes of a virus envelope?

answer

True

question

Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals?

answer

They cannot reproduce themselves outside a host.

question

Package and protect the viral genome

answer

Function of a viral structural elements.

question

Retrovirus

answer

Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?

question

Enveloped viruses

answer

Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?

question

Lysogeny

answer

Lysogenic viral DNA integrating into the host genome is referred to as what?

question

Exposure to UV light

answer

Which of the following events might trigger induction of a temperate bacteriophage?

question

The host cell dies during the lytic stage

answer

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?

question

It is copied every time the host DNA replicates.

answer

What is the fate of the prophage during the lysogenic stage?

question

Prophage

answer

In which stage is the viral DNA introduced into the cell?

question

Assembly

answer

In which stage does formation of mature viruses occur?

question

Synthesis

answer

The host DNA is usually degraged during which stage?

question

The virus would not be able to infect new hosts.

answer

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?

question

Capsomere, Capsid, Nucleocapsid, Virion

answer

The following viral structures are in order from simplest to most complex.

question

Most viruses can infect only certain types of cells.

answer

Most viral genomes are much smaller than the genomes of the cells they infect. Which of the following CANNOT be inferred from this statement?

question

It does not perform the physiological functions carried out by the cytoplasmic membrane

answer

The envelope found in some virus particles differs from the cytoplasmic membrane of cells in what way?

question

Viral capsids

answer

What can assume one of three basic shapes?

question

Envelope

answer

Some viruses have an outer membrane

question

Tobacco virus

answer

What is the first virus to be discovered and characterized?

question

Capsomeres

answer

Subunits that compose viral capsids

question

Icosahedron

answer

20-sided polyhedral capsid

question

Nucleic acid, presence of envelope, shape, size

answer

How viruses are classified

question

Interactions between viral and cellular surface molecules

answer

Host specificity of a virus is due to what?

question

Naked virion

answer

Animal virus that does not have an envelope

question

Cells and viruses

answer

Lipid membrane present in which type of organism?

question

In both cells and viruses

answer

Double-stranded DNA genomes are found in which type of organism?

question

Only in viruses

answer

Double-stranded RNA genomes can be found in which type of organism?

question

Cells only

answer

Cytoplasm is a characteristic of which type of organism?

question

Proteins

answer

These are found in both cells and viruses.

question

Infected cell may live for a long time

answer

Infections with enveloped animal viruses are similar to lysogenic phage infections because

question

Attachment

answer

A phage T4 particle that has lost its tail fibers will have a replication cycle that is blocked at which of the following stages?

question

Uncoating

answer

A process in which viral capsids are removed within the infected cell.

question

Random collisions, chemical attractions, and receptor specificity

answer

Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?

question

Assembly

answer

The phenomenon of transduction is associated with which of the stages of a bacteriophage infection cycle?

question

The genetic material of the bacteriophage can be passed on to future generations of cells

answer

Why is lysogeny advantageous to a bacteriophage?

question

The nuclear and cytoplasmic membranes and the endoplasmic reticulum

answer

Which of the following membranes can give rise to a viral envelope?

question

The HIV provirus is integrated permanently into the host cell's DNA

answer

How is the HIV provirus different from a lambda phage prophage?

question

Latency

answer

During ______, viruses remain dormant in a cell.

question

Lytic

answer

Virus replication results in the death of the cell in a(n) infection.

question

Budding

answer

A mechanism of release for enveloped viruses

question

Virion

answer

Which of the following terms refers to a virus in the extracellular state?

question

Plant

answer

The first virus to be identified was isolated from what type of organim?

question

Protein

answer

The capsid of a virus is made out of which of the following types of molecules?

question

Helical, polyhedral, complex

answer

Basic types of viral shapes

question

They are dependent on host cell organelles and enzymes for their replication.

answer

Why do viruses have to infect host cells?

question

Tail Fibers

answer

The ____ of a bacteriophage are most useful the attachment stage of the lytic replication cycle.

question

Viral DNA becomes a physical part of the bacterial chromosome only in a lysogenic cycle.

answer

Which of the following is a major difference between a lysogenic and a lytic cycle in bacteriophages?

question

Pili, flagella, cell wall

answer

Bacteriophages can use all of the following structures for attachment to a bacterial cell

question

The phage persists for generations in the bacterial chromosome.

answer

What is the advantage of lysogeny to lambda phage

question

Continuous

answer

HeLa cells are an example of a _____ cell culture.

question

contain no nucleic acid

answer

Scientists have determined that prion diseases are not caused by a type of slow virus because prions

question

Spontaneous process

answer

The assembly stage of the viral life cycle is usually a ______, although in some viruses it is controlled by enzymes

question

Induction

answer

A prophage is excised from the host chromosome and viral replication proceeds in a process called _____.

question

Viroids

answer

Small, circular RNA molecules that are infectious to plants are called___

question

Persistent

answer

An infection in which a host cell sheds new viruses slowly and steadily is called a(n) __________ infection.

question

Plaque

answer

A technique used to estimate the numbers of bacteriophages in a culture is called a(n) __________ assay.

question

Spongiform Encephalopathies

answer

As a group, prion diseases are more formally known as ______.

question

an accurate description of a virion?

answer

an infectious particle of protein and nucleic acid outside a host cell

question

The outermost layer of a virion fulfills which of the following functions of the virus?

answer

both protection and recognition

question

A ________ is a virus that infects bacterial cells.

answer

bacteriophage

question

Host specificity of a virus is due to

answer

interactions between viral and cellular surface molecules.

question

The shape of a virion is a function of the ________ of the virus.

answer

capsid

question

The envelope portion of an enveloped virus is composed of

answer

host cell membranes containing virus-encoded glycoproteins.

question

Classification of viruses includes

answer

orders and families

question

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

answer

III, V, I, II, IV

question

Naked capsid animal viruses gain entry to host cells by

answer

both endocytosis and direct penetration.

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

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?

answer

lysogenic

question

Which virus is CORRECTLY matched with its method of entry?

answer

HIV; membrane fusion

question

Retroviruses require the activity of ________ to complete their infection cycle.

answer

reverse transcriptase

question

Which of the following membranes can give rise to a viral envelope?

answer

the nuclear and cytoplasmic membranes, and the endoplasmic reticulum

question

The process of metastasis results from

answer

malignant tumors.

question

The development of a cancerous cell is said to require "multiple hits." This means

answer

a series of separate events over time lead to the loss of cell cycle regulation.

question

Plaque assays are used for

answer

determining the density of phage in a culture.

question

What is one of the most difficult aspects of studying animal viruses?

answer

The use of animals is expensive, and unethical to many people.

question

Infection with ________ is likely to result in destruction of the host cell by lysis.

answer

naked viruses

question

Some human viruses are difficult to study because

answer

they only grow in normal human cells.

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

Small circular RNA molecules without capsids are characteristic of

answer

viroids.

question

Prions cause disease in

answer

mammals.

question

A ________ is a mass of neoplastic cells.

answer

tumor

question

The process known as ________ is a mechanism of release for enveloped viruses.

answer

budding

question

Viruses cause most human cancers.

answer

false

question

Virus entry requires the presence of specific cell structures.

answer

true

question

Protozoa are susceptible to viral attack.

answer

true

question

All members of a virus family have the same type of genome structure.

answer

true

question

Bacteriophage release is a gradual process in which small numbers are released at a time.

answer

false

question

Fertilized chicken eggs are used to culture some vaccine strains

answer

true

question

The combination of a virus's protein coat and nucleic acid core is called the ________

answer

nucleocaspid

question

The first virus isolated, Tobacco mosaic virus, has a ________ capsid morphology, which facilitated its isolation.

answer

helical

question

Some viruses can be cultured on ________ cells which are descended from neoplastic cells.

answer

continuous

question

The process in which viral capsids are removed within the infected cell is called ________

answer

uncoating

question

Genes that play a role in proper cell division but may also play a role in some types of cancer are called ________

answer

protooncongenes

question

A ________ is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.

answer

plaque

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

Which of the following is a characteristic by which viruses are classified?

answer

type of nucleic acid

question

Which of the following is primarily responsible for the shape of a virion?

answer

the capsid

question

How are fungal viruses different from viruses that infect other organisms?

answer

They have no extracellular state

question

Which of the following infectious particles do NOT have protein in their structure?

answer

viroids

question

Which of the following may occur in a lysogenic infection, but not a latent one

answer

The inserted viral DNA may leave the host DNA.

question

Which of the following statements regarding virus taxonomy is true?

answer

Some virus family names are derived from the name of an important member of the family.

question

Which of the following statements comparing virus classification and taxonomy of organisms is true?

answer

Genus and specific epithet are used in both classification systems

question

Which of the following places stages of a lytic replication cycle in order, from earliest to latest stages?

answer

III, V, I, II, IV

question

Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?

answer

random collisions, chemical attractions, and receptor specificity

question

The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle?

answer

entry and release

question

Which means of entry into host cells is common to both some animal viruses and bacteriophage T4?

answer

direct penetration

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

Which of the following agents is capable of inducing conversion of a prophage to the lytic cycle

answer

both UV light and X-rays

question

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?

answer

lysogenic

question

Which of the following is matched INCORRECTLY?

answer

adenovirus; membrane fusion

question

Reverse transcriptase is associated with which of the following?

answer

retroviruses

question

The genome of which of the following types of animal virus can act directly as mRNA?

answer

+ssRNA viruses

question

Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated?

answer

-ssRNA viruses

question

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

answer

a DNA polymerase.

question

Which of the following membranes can give rise to a viral envelope?

answer

the nuclear and cytoplasmic membranes and the endoplasmic reticulum

question

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?

answer

neoplasia

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

Which of the following laboratory procedures is used for culturing animal viruses in the laboratory?

answer

both cell cultures and embryonated eggs

question

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?

answer

retroviruses

question

Tumors invade other organs and tissues in a process called

answer

metastasis

question

Plaque assays are used for

answer

determine the density of phage in a culture

question

Diploid cell cultures and continuous cell cultures differ in which of the following ways?

answer

both longevity and source of cells

question

Viroids infect

answer

plants

question

The viruses of fungi have RNA genomes and lack a capsid. They are therefore similar to

answer

prions

question

A lipid membrane is present in which of the following?

answer

enveloped viruses

question

Some human viruses are difficult to study because

answer

they only grow in normal human cells.

question

Double-stranded RNA genomes can be found

answer

only in viruses

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

Small circular RNA molecules without capsids are characteristic of

answer

viroids

question

Viruses are shed slowly and steadily during

answer

lysogenic infection.

question

During ________, viruses remain dormant in animal cells.

answer

latency

question

Virus replication results in the death of the cell in ________ infection(s).

answer

a lytic

question

A ________ is a mass of neoplastic cells.

answer

tumor

question

The process known as ________ is a mechanism of release for enveloped viruses

answer

budding

question

Viruses cause most human cancers.

answer

false

question

Most viruses cannot be seen by light microscopy

answer

true

question

Protozoa are susceptible to viral attack.

answer

true

question

Many diseases of plants are caused by infectious RNA molecules lacking capsids

answer

true

question

Assembly of new viruses is a process that usually requires the direction of a variety of viral and cellular enzymes.

answer

false

question

Bovine spongiform encephalopathy is an example of a prion disease.

answer

true

question

All viruses use the host cell's nucleic acid polymerases for replication

answer

false

question

The combination of a virus's protein coat and nucleic acid core is called the (capsid/virion/nucleocapsid).

answer

nucleocapsid

question

Viral capsids are composed of subunits called (nucleocapsids/capsomeres).

answer

capsomeres

question

Virus infection is initiated by the specific (fit/affinity/interaction) between proteins on the surface of a virion the surface of the target cell.

answer

affinity

question

Some viruses can be cultured on (continuous/diploid/animal) cells which are descended from neoplastic cells.

answer

continuous

question

The virions shown in the figure have a (polyhedral/helical/complex) capsid.

answer

complex

question

Another term for a lysogenic phage is a (temperate/latent/prophage) phage

answer

temperate

question

The process in which viral capsids are removed within the infected cell is called (entry/disassembly/uncoating)

answer

uncoating

question

Uncontrolled cell division in animals is known as (metastasis/neoplasia/cancer).

answer

neoplasia

question

RNA viruses such as HIV require the activity of reverse (transcriptase/polymerase) to become proviruses.

answer

transcriptase

question

In enveloped viruses, virus-encoded (matrix/capsomeres/envelope) proteins are required for the assembly of the envelope around the capsid.

answer

matrix

question

A (colony/plaque) is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.

answer

plaque

question

Three (orders/families/classes) represent the highest level of taxonomic rank used in classifying viruses.

answer

orders

question

Prions are composed of a single protein called (plaque/BSE/PrP).

answer

PrP

question

An animal virus that does not have an envelope is described as a(n) (naked/unenveloped/capsid) virion

answer

naked

question

How does specialized transduction differ from regular lysogeny?

answer

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

question

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?

answer

The host DNA integrates, with the prophage, into the new recipient chromosome

question

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?

answer

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

question

Which of the following is true concerning a lysogenic viral replication cycle?

answer

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

question

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.

answer

They require a host in order to reproduce.

question

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

answer

To package and protect the viral genome

question

Lysogenic viral DNA integrating into the host genome is referred to as a prophage. induction. lytic. lysogeny.

answer

a prophage

question

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

answer

Exposure to UV light

question

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.

answer

It is copied every time the host DNA replicates.

question

Which virus employs the use of an RNA-dependent RNA polymerase?

answer

+RNA viruses

question

Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?

answer

Retroviruses

question

Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?

answer

Enveloped viruses

question

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

answer

+RNA

question

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

answer

attachment

question

What occurs during viral uncoating?

answer

the capsid breaks apart, releasing the viral genome

question

Which of the following is true regarding cultivation and isolation of animal viruses?

answer

Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host

question

Which disease did Stanley Prusiner first identify as being caused by prions?

answer

Scrapie

question

The normal function of the PrP protein in mammals is believed to be:

answer

assisting in normal synaptic development and function.

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

What disease does the human herpesvirus-1 cause? canker sores chancres cold sores or fever blisters infectious mononucleosis

answer

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?)

question

What is the correct sequence of events for the replication of a DNA virus? Arrange the following statements in chronological order .

answer

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.

question

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

answer

-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.

question

Which of the following are symptoms of influenza infection?

answer

-muscle pain -headache -fever

question

Which of the following statements regarding antigenic shift are true?

answer

-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

question

Predict which of the following are reasonable outcomes of the cytokine storm during the 1918 flu pandemic.

answer

-increased fluid in the lungs and labored breathing -an excessive inflammatory response leading to extensive tissue damage

question

What are some of the current challenges to production of the influenza vaccine?

answer

-in order to yield a vaccine, the virus must be produced in eggs -the virus undergoes antigenic changes on a regular basis

question

Predict which of the following would be outcomes of treatment with Tamiflu.

answer

-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

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

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

Which disease did Stanley Prusiner first identify as being caused by prions?

answer

Scrapie

question

The normal function of the PrP protein in mammals is believed to be:

answer

Assisting in normal synaptic development and function

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

Which of the following diseases is NOT caused by prions?

answer

Chagas' disease

question

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?

answer

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

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

question

Is this disease contagious?

answer

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

question

Which test confirmed the presence of this prion disease?

answer

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

question

What is the typical incubation period for prion disease?

answer

Decades Prion diseases are usually apparent decades after the initial exposure.

question

Label the lesions of the human herpesvirus that occur at various locations on the human body.

answer

Ocular herpes- eyes Fever blisters- around the mouth Genital herpes- penis Whitlow- fingers

question

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?

answer

Papillomavirus Papillomaviruses can produce warts in susceptible hosts

question

Is it possible for Rudy's warts to spread to other areas of his body?

answer

Yes. Papillomaviruses are spread by direct contact. This is called autoinoculation.

question

What type of cancer is more likely to develop in people who have had papillomavirus infections?

answer

cancer of the tonsils Papillomavirus infections increase the risk of cancer in the tonsils fourteenfold

question

Which of the following is NOT an accepted treatment for warts?

answer

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.

question

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?

answer

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)

question

Which nucleic acid is part of the varicella-zoster viron?

answer

dsDNA The varicella-zoster virus contains dsDNA

question

Is Grandfather Davis contagious?

answer

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.

question

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

answer

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

question

What type of vaccine would be used to vaccinate the twins?

answer

Attenuated virus vaccine The vaccine for chicken pox contains an attenuated virus

question

All of these statements are characteristics of VZV infections EXCEPT ____.

answer

A person can get shingles from a person who has chickenpox

question

In what way does a seed wart differ from a flat wart?

answer

The location of the wart

question

Shingles, or herpes zoster, is a reactivation of the virus that causes

answer

chickenpox

question

Common skin warts are the result of infection with

answer

papillomaviruses

question

Some strains of Papillomavirus are oncogenic due to their ability to

answer

Integrate into the host cell DNA

question

The rash described as "teardrops on rose petals" is characteristic of

answer

chickenpox

question

Chickenpox and (herpes/shingles/warts) are caused by the same virus

answer

shingles

question

Localization of lesions within a band of skin on one side of the body is a characteristic of the disease (measles/shingles/sporotrichosis)

answer

shingles

question

Warts on the sole of the foot are known as (seed/flat/plantar) warts

answer

plantar

question

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?

answer

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.

question

Which of the following best explains why Tori developed a new series of symptoms?

answer

The antibiotics that treated Tori's primary respiratory infection also removed some of her normal bacterial flora, resulting in an overgrowth of other organisms.

question

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?

answer

Oral thrush and fulminating disease

question

Which of the following statements best describes why the treatment for Tori's fungal infection may result in side effects to her own cells?

answer

Fungal cells and human cells have a nucleus, multiple organelles, and 80S ribosomes for protein synthesis

question

How do blastoconidia and chlamydoconidia produced by yeast differ from bacterial endospores?

answer

Blastoconidia and chlamydoconidia are spore structures produced by budding in yeasts, whereas bacterial endospores are produced by bacteria under extreme conditions

question

How do pseudohyphae in yeasts differ from vegetative hyphae in filamentous fungi?

answer

Yeasts us pseudohyphae to invade host tissue, whereas filamentous fungi use their vegetative hyphae for obtaining nutrients

question

Which of the following could cause athlete's foot?

answer

Trichophyton species

question

"Ringworm" is caused by

answer

dermatophytes growing in the upper dead tissue layers of the skin

question

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

answer

chromoblasomycosis

question

Because they are common soil saprobes, dermatophytes are fungi that are not contagious in humans

answer

False

question

Chromoblastomycosis is rarely a sever disease and can be treated easily with appropriate drugs.

answer

False

question

Which disease did Stanley Prusiner first identify as being caused by prions?

answer

scrapie

question

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

answer

prophage

question

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

answer

Exposure to UV light

question

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.

answer

It is copied every time the host DNA replicates.

question

Which virus employs the use of an RNA-dependent RNA polymerase?

answer

+RNA viruses

question

Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?

answer

retroviruses

question

Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane? +RNA viruses dsRNA viruses Naked viruses Enveloped viruses

answer

enveloped viruses

question

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

answer

+RNA

question

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.

answer

Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).

question

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.

answer

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.

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/maturation

question

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.

answer

The virus would not be able to infect new hosts.

question

Name the human disease caused by prions?

answer

Creutzfeldt-Jakob disease (CJD)

question

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?

answer

attachment

question

What occurs during viral uncoating?

answer

The capsid breaks apart, releasing the viral genome.

question

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.

answer

Latent infections can persist for years in an individual without causing any symptoms.

question

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.

answer

Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA.

question

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.

answer

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

question

Which virus is NOT associated with cancer? ANSWER: Epstein-Barr virus (EBV) coronavirus human papillomavirus (HPV) hepatitis B virus (HBV)

answer

coronavirus

question

The normal function of the PrP protein in mammals is believed to be:

answer

assisting in normal synaptic development and function.

question

Why are the beta-pleated multimers of PrP potentially pathog

answer

The multimers are more stable and resistant to protease.

question

Which of the following statements describes a generalist virus?

answer

It infects many kinds of cells in many different hosts

question

All of these are steps in the lytic cycle of a temperate bacteriophage. Which happens second?

answer

1. attachment *2. ENTRY 3. bacterial chromosome degraded 4. synthesis 5. assembly 6. release

question

Which of the following is NOT represented in viral classification schemes?

answer

1. order 2. family 3. genus 4. specific epithet *class is NOT

question

Which of the following diseases is NOT caused by prions?

answer

1. Bovine Spongiform Encephalitis 2. Kuru 3. Scrapie *Chagas' disease is NOT

question

Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4?

answer

Entry and Release

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 (such as endocytosis or active transport)

question

Which of the following is an essential component of all viruses?

answer

a. ribosomes *b. capsid- all viruses have a capsid surrounding their nucleic acid c. envelope d. DNA

question

Lysogeny refers to...?

answer

viral DNA becoming imbedded within the host cell's chromosomes.

question

Lysogeny is associated with all of the following EXCEPT... a. bacteriophages b. animal viruses c. increasing virulence of host bacterium d. a prophage

answer

Animal viruses do not undergo lysogeny.

question

Put the following viral structures in order, from simplest to most complex: I. virion II. capsomere III. capsid IV. nucleocapsid

answer

capsomere capsid nucleocapsid virion

question

Viruses can be grown in all of the following EXCEPT __________. a. embryonated eggs b. tissue culture c. sterile nutrient agar d. live animals

answer

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.

question

You have isolated bacterium that contains a prophage. Which of the following is true concerning the prophage?

answer

The phage is in the lysogenic cycle

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. Each plaque on the plate corresponds to a single phage.

question

Which of the following would be an appropriate mode of action for a new anticancer drug?

answer

inactivation of an oncogene

question

Which of the following types of enzymes is necessary for the replication of most double-stranded DNA (dsDNA) viruses?

answer

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.

question

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.

answer

b. Most viruses can infect only certain types of cells.

question

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

answer

b. they live inside host cells

question

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

answer

attachment

question

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

answer

disruption of cell division

question

Contact between a phage and its bacterial host occurs by _____.

answer

a random collision

question

What portion of bacteriophage T4 enters E. coli?

answer

Only the T4 genome enters the bacterial cell.

question

Once entry into the bacterial cell has been achieved, the next step in a lytic replication cycle is _____.

answer

Only the T4 genome enters the bacterial cell.

question

During a lytic replication cycle, what action does a phage take to ensure that its host bacterium does NOT continue synthesizing cellular molecules?

answer

Phage enzymes degrade the bacterial DNA.

question

In a lytic cycle of replication, release of phages involves _____.

answer

the bacterial cell bursting open

question

A major difference between the lytic and lysogenic cycles of phage replication is that during the lysogenic phase _____.

answer

the phage genome inserts itself into the host genome

question

What factor may induce a prophage to enter the lytic cycle?

answer

UV light

question

During the lysogenic cycle, it is possible for integrated phage genes to change the characteristics of the host cell. This is known as _____.

answer

lysogenic conversion

question

What is the function of the structural elements of a virus?

answer

to package and protect the viral genome

question

Lysogenic viral DNA integrating 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

What is the fate of the prophage during the lysogenic stage?

answer

it is copied every time the host DNA replicates

question

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?

answer

attachment

question

What occurs during viral uncoating?

answer

the capsid breaks apart

question

The normal function of the PrP protein in mammals is believed to be:

answer

assisting the normal synaptic development and function

question

Why are the beta-pleated multimers of PrP potentially pathogenic?

answer

The multimers are more stable and resistant to protease

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. Because enveloped viruses are shed slowly and persistently from the host cell by budding, the host cell may survive for a long time.

question

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

answer

d) assisting in normal synaptic development and function

question

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

answer

d) The multimers are more stable and resistant to protease

question

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

answer

d) It infects many kinds of cells in many different hosts

question

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

answer

b) have no extracellular state

question

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.

answer

d) they do not contain nucleic acids.

question

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

answer

a) cellular DNA polymerase

question

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

answer

b) attachment

question

Which of the following is the midpoint of a lytic replication cycle? a) release b) attachment c) entry d) synthesis

answer

d) synthesis

question

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

answer

a) different strains have various kinds of genetic abnormalities

question

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

answer

b) attachment

question

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

answer

a) The capsid breaks apart, releasing the viral genome

question

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

answer

c) Scrapie

question

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.

answer

d) They require a host in order to reproduce

question

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

answer

a) To package and protect the viral genome

question

Which of the following is NOT represented in viral classification schemes? a) class b) genus c) family d) specific epithet

answer

a) class

question

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

answer

c) entry and release

question

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

answer

c) 20

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