Microbiology- Chapter 6
Which of the following term describes the total nucleic content of a virus? Gene mRNA DNA Genome Chromosome Capsid
Genome
Why are CD4 counts related to HIV infection?
HIV can only bind to cells with CD4 receptors.
Identify the different environments in which some viruses can replicate. Saliva Human cells Freshwater Bacterial cells Animal cells Marine water
Human cells Bacterial cells Animal cells
Which of the following viral structures typically make enveloped viruses very species-specific for the host cell they infect?
Receptors in the envelope
Which of the following structures of enveloped viruses must be specific for adsorption?
Spike proteins
What name is given to a phage "type" which can incorporate itself into the host genome as a lysogenic prophage?
Temperate
Which is NOT a reason that eggs provide an excellent in vivo viral cultivation system? The egg contains a tissue monolayer The interior environment of the egg is sterile The egg is self-supporting
The egg contains a tissue monolayer
True or false: Inoculation of laboratory animals is an in vivo method of viral cultivation.
True
True or false: Viral nucleic acid may be single-stranded or double-stranded DNA or RNA.
True
True or false: Viruses are among the smallest infective agents.
True
Identify the smallest pathogenic agent. Virion Fungal cell Bacterial cell Helminth
Virion
Choose the statement that correctly explains why viruses are referred to as "filterable." Viruses are able to pass through a filter because of their high density. Viruses are able to pass through a filter because of their small size. Viruses are able to pass through a filter because they lack peptidoglycan in their envelope. Viruses are able to pass through a filter because of the negative charge on their surface. Viruses are not able to pass through filters.
Viruses are able to pass through a filter because of their small size.
Viruses ______ depend on a host cell for replication. completely partially never
completely
Where are most RNA viruses replicated and assembled within the host?
cytoplasm
The 2 principle processes by which viruses penetrate host cells are BLANK (engulfment) and direct fusion.
endocytosis or phagocytosis
Hepatitis viruses have a tropism for cells of the ______.
liver
Phage DNA that is latently incorporated into the bacterial host genome is called a BLANK
prophage
At minimum, viruses are composed of nucleic acid covered by a coating comprised of BLANK
protein
A BLANK is a protein subunit that forms the viral capsid.
capsomere
Viral nucleic acids are ______. -either single-stranded or double stranded -single-stranded only if RNA -double stranded only -single-stranded only
either single-stranded or double stranded
The process of BLANK, a type of penetration, occurs when viruses are taken into the cell followed by engulfment in a vacuole or vesicle.
endocytosis or phagocytosis
In which way do enveloped viruses leave their host cell?
Budding
Which of the following viral release methods will not initially destroy the cell?
Budding
Which is closest in physical proximity to the nucleic acid of a virus? Envelope Capsid Spike
Capsid
Which structure immediately encloses viral nucleic acid?
Capsid
Identify the virus types which are released from host cells by lysis.
Complex Naked
Which term is used to describe the phospholipid bilayer found surrounding the capsid of some viruses? Vacuole Phagosome Cell membrane Envelope
Envelope
Choose the term that describes a virus that has a membranous outer covering over its capsid. Encapsulated virus Coated virus Naked virus Enveloped virus Icosahedral virus
Enveloped virus
Which types of viruses are released by budding? DNA viruses Enveloped viruses RNA viruses Naked viruses
Enveloped viruses
Choose the statement that indicates how cytopathic effects are detected. Performing immunological tests on infected cells Performing biochemical tests on infected cells Examining infected cells with a microscope Growing infected cells in a variety of different media
Examining infected cells with a microscope
Identify any of the following pathways which could produce proteins used by viruses. Host DNA --> mRNA --> proteins used by viruses Viral negative-ssRNA --> proteins used by viruses Viral positive-ssRNA --> proteins used by viruses
Host DNA --> mRNA --> proteins used by viruses Viral positive-ssRNA --> proteins used by viruses
Which of the following is a term used to describe the different host cells which a virus can infect? Compatible range Spread Virus range Host range
Host range
BLANK bodies are masses of viruses or damaged organelles of a cell due to a cytopathic effect of viral infection.
Inclusion
Which of the following is a mass of viruses or damaged organelles due to the cytopathic effect of viral infection? Inclusion body Syncytium Neoplasm
Inclusion body
How does bacteriophage nucleic acid enter the host cell?
Injection
Choose the term that describes a bacteriophage infection in which the host bacteria are lysed and killed by the infection.
Lytic
______ active viral infections lead to cell death.
Most
A single virion could contain a genome of: RNA only DNA only both RNA and DNA neither RNA or DNA
RNA only DNA only
An envelope is acquired during which step of the viral life cycle?
Release
Which are the three main criteria used in classifying viruses into families? Structure Genetic makeup Cell type infected Chemical composition Pathogenic potential Geographic distribution
Structure Genetic makeup Chemical composition
Which term describes the integration of an oncogenic virus that changes mammalian host DNA? Lysogeny Transduction Transformation
Transformation
True or False. A portion of the viral envelope comes from the cell membrane of the host cell.
True
True or False. Both enveloped and naked viruses can enter a cell by endocytosis.
True
True or false: Budding viruses do not lyse the host cell during release.
True
True or false: Embryonic tissue can serve as a primary cell line for viral culture.
True
Virus X can infect rodents and birds, whereas Virus Y infects humans. Which has a broader host range?
Virus X
During the BLANK step in the viral multiplication cycle, capsids and genetic material are packaged into virions. Please give the specific term for this step.
assembly
Any virus that specifically infects bacteria is called a(n) BLANK
bacteriophage
Most bacteriophages contain which type of nucleic acid?
dsDNA
Every virus particle contains _____.
either DNA or RNA
An BLANK virus has a membranous layer external to the nucleocapsid.
enveloped
The total nucleic acid content of a virus can be referred to as the viral BLANK.
genome
Lysogeny is best described as ______.
integration of the viral genome into the host chromosome
Typically, naked helical viruses are ______ flexible than enveloped helical viruses.
less
When a temperate phage infects a bacterium which gives the bacterium new traits, this is called ______.
lysogenic conversion
When present, what is the viral envelope composed of?
mainly lipids
A nonenveloped virus is also called a(n) ______ virus.
naked
Capsids of ______ helical viruses are rigid and tight, while capsids of ______ helical viruses are flexible and loose.
naked; enveloped
The BLANK refers to the capsid and nucleic acid of a nonenveloped virus.
nucleocapsid
Where are most DNA viruses replicated and assembled within the host?
nucleus
Viruses that are BLANK lead to cancer in infected hosts.
oncogenic
"Virus" is Latin for ______.
poison
Which macromolecule composes capsomeres?
proteins
A BLANK is the stage of an animal virus life cycle which is integrated into the host cell's genome.
provirus
HIV is described as a(n) BLANK because it synthesizes DNA from RNA using reverse transcription.
retrovirus
Identify all the types of nucleic acid genomes which have been discovered carried by various bacteriophages. ssRNA Both RNA and DNA in a single phage Both ss and ds RNA in a single phage ssDNA dsDNA Both ss and ds DNA in a single phage
ssRNA ssDNA dsDNA
A BLANK phage is a bacteriophage that incorporates itself into the host genome as a lysogenic prophage.
temperate
In viral entry by endocytosis _______.
the host cell's plasma membrane surrounds the whole virion and forms a vesicle
Some strains of human papillomavirus (HPV) can cause cellular changes that lead to the development of cervical cancer. Infections by such oncogenic viruses are known as _______.
transforming infections
Almost immediately upon entry, the viral nucleic acid alters the genetic expression of the host cell.
true
A fully formed virus that is able to establish an infection in a host cell is often called a ______.
virion
A single virus particle is known as a(n) BLANK
virion
A virus that parasitizes another virus is called a(n) ______.
virophage
Louis Pasteur proposed the term ______, Latin for "poison", to denote a special group of infectious agents.
virus
List the correct order of viral life cycle phases, starting with the first at the top.
1.) Absorption 2.) Penetration/Uncoating 3.) Synthesis 4.) Assembly 5.) Release
Which is the correct term to describe viral adherence to a host cell receptor? Adsorption Penetration Absorption
Adsorption
Choose the primary reason why it is more difficult to design antiviral drugs than antibacterial drugs. Antiviral drugs must target viral envelopes and capsids. Viral cell structure is different than bacterial cell structure. Antiviral drugs can't readily penetrate host cells. Antiviral drugs often must target host cell functions, which results in side effects in the host.
Antiviral drugs often must target host cell functions, which results in side effects in the host.
True or False. A naked virus fuses with the host cell membrane.
False
True or False. All viruses leave a cell by exocytosis.
False
True or False. Animal viruses always kill cells they infect.
False
True or False. Viruses can be grown on culture media like bacteria.
False
True or false: Chicken eggs have a monolayer of cells within them which offer a good place to propagate virus.
False
Through the process of BLANK, a prophage is activated and enters the lytic cycle.
Induction
What term is used to define the process of a prophage being activated and entering into the lytic cycle?
Induction
Which term refers to the persistence of bacteriophages within host cells?
Lysogeny
Which of the following best describe the relationship between viruses and their host cell? Parasitism Mutualism Commensalism
Parasitism
BLANK infections are those which cells are infected yet show no cytopathic effects.
Persistent
A cell harboring a virus that is not causing cytopathic effects is characteristic of which type of infection?
Persistent infection
Bacteriophages can infect which of the following? Eukaryotes only Both prokaryotes and eukaryotes Prokaryotes only
Prokaryotes only
Capsomeres are composed of BLANK. (Hint: it is a macromolecule)
Protein
Which of the following best describes a prion? Proteinaceous infectious agent RNA-based infectious agent Obligate aerobe Obligate intracellular parasite
Proteinaceous infectious agent
At minimum, all viruses are composed of: Proteins Carbohydrates Lipids Nucleic acids
Proteins and nucleic acid
Choose the phrase that best describes the role of viral surface proteins or spikes. Allow viruses to bind to each other Enable replication of the viral nucleic acid Provide means for viruses to exchange nucleic acid Provide means of attachment to host cell surface Inject viral nucleic acid into host cell
Provide means of attachment to host cell surface
What are viruses called which are capable of converting their RNA genomes into DNA?
Retroviruses
What will happen once a virus has entered a host cell and uncoated?
The synthesis of new virions will occur.
Which two of the following mechanisms are found to result in cancer caused by a virus? The virus carries genes that can cause the cancer. Viruses carry genes from an existing tumor to other body sites to cause cancer. Viral proteins cause changes in growth regulation, leading to cancer. Bacteriophages from host microbiota infect host cells to cause cancer.
The virus carries genes that can cause the cancer. Viral proteins cause changes in growth regulation, leading to cancer.
True or false: Bacteriophages can contain double-stranded or single-stranded DNA or RNA.
True
True or false: Both naked and complex viruses are released from host cells via lysis once mature.
True
True or false: Most active viral infections lead to cell death regardless of the type of release process.
True
Which term describes the process of a virus losing its capsid and exposing viral nucleic acids to the immediate environment?
Uncoating
Viral spikes _______.
attach specifically to host cell receptors
In the release process, the viral capsid _______.
becomes completely enclosed by the region of the cell membrane into which the spikes and matrix protein are embedded
Rabies virus has a _______ host range as compared to hepatitis B virus.
broad
Two ways in which newly assembled viruses are released from host cells are through BLANK (exocytosis) by enveloped viruses, and through BLANK (rupture) by naked viruses.
budding, lysis
Budding is a type of ______ process where enveloped viruses are released from the host cell membrane.
exocytic
Two shapes of viral capsids are BLANK, which resembles a bracelet; or BLANK, which is a type of polyhedron.
helical, icosahedral
Which term correctly refers to viral bursting of any host cell?
lysis
A BLANK is a proteinaceous infectious agent associated with spongiform encephalopathies.
prion
Mad cow disease is caused by a noncellular infectious agent called a ______.
prion
Viral capsids are composed of _____.
protein
An enzyme capable of taking an RNA genome and generating a DNA copy is called ______.
reverse transcriptase
In some viruses, including HIV, the enzyme BLANK BLANK transcribes RNA into DNA.
reverse transcriptase
Most human viral infections are ______.
self-limiting
Enveloped viruses use glycoproteins called _______ to specifically bind with their host cells.
spikes
What term is used to describe the viral proteins which protrude from the envelope and aid in attachment to host receptors?
spikes
A virus that only infects cells of a specific tissue in the body is described as having a ______.
tropism
The term "in BLANK" implies that a virus is being propagated in a living animal.
vivo
Some retroviruses carry oncogenes that may incorporate into the host cell DNA and ultimately result in ______.
cancer
The structure directly surrounding the viral nucleic acid is the BLANK, a coat of proteins.
capsid
Different viruses can infect which of the following? -Human, bacterial, or plant cells -Plant cells only -Human cells only -Bacterial cells only
-Human, bacterial, or plant cells
At a minimum, a viral genome must include genes for: (choose all that apply) -regulating the actions of the host cell -synthesizing new ribosomes following infection -generating ATP for energy -synthesizing the viral capsid -packaging the mature virus particles
-regulating the actions of the host cell -synthesizing the viral capsid -packaging the mature virus particles
Which two of the following statements about virophages are correct? A virophage uses genes from another virus for its own replication. Virophages are being developed to treat cancers caused by oncogenic viruses. Virophages are specific for the AIDS virus, and are being developed as a vaccine. A virophage is a virus that parasitizes another virus.
A virophage uses genes from another virus for its own replication. A virophage is a virus that parasitizes another virus.
BLANK is the viral process of attaching to the host cell receptor for the virus.
Adsorption
If you could design a drug to "hide" or block sialic acid on respiratory cells, what stage of the life cycle of influenza would be directly impacted?
Adsorption
Identify any of the following which can be used as primary cell lines. Fetal cells Cancer cells Embryonic tissue Any of the answers listed here Adult tissue cells
Any of the answers listed here
Which of the following describes the various viral parts coming together to produce virions? Assembly Penetration Release Absorption
Assembly
Which of the following is the monomeric unit for a viral capsid? Facet Fiber Capsomere Amino acid Protein
Capsomere
True or false: Most bacteria engulf bacteriophages as part of the phage replication strategy.
False
True or false: Viruses which can lead to cancer are termed carcinoviruses.
False
True or false: The viral envelope and capsid are the same thing.
False. Reason: The viral envelope is composed of phospholipids while the capsid is composed of capsomer proteins.
Identify all the methods that a virus can use to gain entry into an animal cell.
Fusion of the viral envelope and the cell membrane Engulfment/phagocytosis of the virus
Identify all the components of the nucleocapsid. Nucleic acid Polymerase Scaffolding proteins Capsid Envelope
Nucleic acid Capsid
In animal viruses, newly made BLANK is used to synthesize viral proteins.
RNA
Which of the following statements regarding the membrane on an enveloped virus is true? -The membrane gives the virus particle a distinct shape. -Viruses insert their own proteins in the membrane. -The membrane is identical to the host cell membrane. -The viral envelope is not a lipid bilayer.
Viruses insert their own proteins in the membrane.
The membrane receptors that viruses attach to during adsorption are typically composed of ______. phospholipids glycoproteins lipids nucleic acid
glycoproteins
Viruses which have a series of rod-shaped capsomer proteins linked together forming a series of interconnected hollow discs are termed ______.
helical
The BLANK range defines the limitations of the type of cell that a virus can invade.
host
Viral transformation implies ______.
host DNA is changed
Viral transformation implies ______. viral genome is changed virus brings exogenous DNA host DNA is changed viral capsid and/or spikes are changed
host DNA is changed
When an enveloped virus buds off the cell membrane, the membrane differs ______ from the host cell's membrane. modestly not at all significantly
significantly
Viruses are classified into families based on genetic makeup, chemical composition, and ______.
structure
A BLANK occurs when a virus induces multiple cells to fuse making a large multinucleated cell.
syncytium
The process of BLANK occurs when viruses lose their envelope during penetration into a host cell or when the envelope/capsid is are dissolved within a vacuole.
uncoating
Genes for synthesizing the viral capsid, for regulating actions of the host cell, and for packaging the mature virus are found in the ______ genome.
viral
The first event to occur in the release of an enveloped virus is the _______.
viral spike proteins are inserted into host cell membrane
Which factor enables certain laboratory animals to propagate viruses more readily than others? Whether or not a virus can infect the bacteria carried by particular animal hosts Receptor specificity between virus and particular animal hosts Immune status of particular animal hosts
Receptor specificity between virus and particular animal hosts
Which is most important for attachment of a virus to a host cell? Viral specificity for host receptors Viral shape and size Number of genes carried by the virus
Viral specificity for host receptors