Micro ch.5 viral structure and multiplication
viroids are composed of naked _____ strands
RNA
viroids are composed of only naked
RNA
a single virus particle could contain a genome consisting of
RNA only and DNA only
what are viruses called which are capable of converting their RNA genomes into DNA?
Retroviruses
it is well known that ____ have no effect on treating viral infections
antibiotics
which of the following are properties of bacterial cells but not of viruses
are able to make ATP for energy and contain ribosomes for protein synthesis
new virons are built from their components during the ___ phase of the viral life cycle
assembly
which of the following describes the various viral "parts" coming together to produce virus particles?
assembly
any virus that specifically infects bacteria is called a(n)
bacteriophage
embryonic eggs are ___________
completely sterile
The word _____ is used to describe viruses which have a non-icosahedral or non-helical arrangement of capsomer proteins.
complex
which os the typical route of infection for mad cow diesease
consumption of contaminated food
which of the following are properties of viruses but not of bacterial cells
contain a protein shell surrounding the genome and nuclide acid as RNA
viral DNA polymerase genes are expressed during the ____ stage of the synthesis phase of the viral life cycle
early
viral nucleic acids are
either single stranded or double stranded
the best method to visualize viruses is
electron microscopy
The process of ______ a type of penetration occurs when viruses are taken into the cell followed by engulfment in a vacuole or vesicle.
endocytosis
identify all the methods that a virus can use to gain entry into an animal cell
engulfment/phagocytosis of virus -fusion of the viral envelope and the cell membrane
Naked viruses do not possess a(n) _________
envelope
a(n) virus has a membranous layer external to the nucleocapsid
enveloped
comparing viral and bacterial genomes, viruses have _____ genes
fewer
which cellular organisms can viruses infect
fungi animals plants protozoa bacteria
the total nucleic acid content of a virus can be referred to as the viral ________
genome
which of the host cell structures must usually be specific for adsoprtion
glycoprotein receptors
viruses typically attach to what type of host membrane receptors?
glycoproteins
the ___ range defines the limits of the type of cell a virus can invade
host
If the term "dead" is used to describe a particular bacterial cell then the term ______ would be used to describe a virus in a similar condition.
inactive
_____ bodies are masses of viruses or damaged organelles of a cell due to a cytopathic effect of viral infection.
inclusion
which of the following are cytopathic effects in virally infected animal cells?
inclusion bodies and syncytia
what term is used to define the process of a prophage being activated and entering into the lytic cycle?
induction
how does T-even bacteriophage nucleic acid enter the host cell?
injection
which of the following are in vivo methods for viral cultivation?
inoculation chicken eggs with viruses inoculating mice with viruses
what was the significance of the discovery of filterable viruses
it showed that infections could be caused by agents that were smaller than bacteria
when bacteriophages infect pathogenic bacteria resulting in a new pathogenic trait called _________ _________
lysogenetic conversion
when a bacterium acquires a new trait from its temperate phage it is called ______
lysogenic conversion
_____ is the persistence of bacteriophage DNA within a host chromosome
lysogeny
the term ____ refers to the persistence of bacteriophages within host cells
lysogeny
what is the common name of bovine spongiform encephalopathy
mad cow disease
cultured cells grow in the form of a ____, a single confluent sheet of cells that support viral multiplication
mono-layer
a nonenveloped virus is called a _____ virus
naked
all viruses must infect a cell host to replicated and therefore they are referred to as ______ intracellular parasites
obligate
Viruses that are ______ lead to cancer in infected hosts
oncogenic
____ is the term for a virus that causes tumors
oncovirus
which of the following best describes the relationship between viruses and their host cell
parasitism
identify the commonalities btn temperate phages and lytic phages
penetration biosynthesis of viral components adsorption release assembly
what is the term which describes the clear area where a virus infected cell lysed and infected all the neighboring cells and lysed those too
plaque
a(n) _____ is observed as a clear area where virus infected monolayers of cells have been disrupted or destroyed
plawue
order the following microbes from smallest to largest
polio virus, streptococcus cell, yeast cell
____ is a name given to a disease-causing agent composed of only protein
prion
which agent is the cause of spongiform encephalopathy
prion
besides viruses, two noncellular infectious agents known as ___________ and viroids are medically important
prions
which of the following is used to describe the phage DNA that is latently incorporated into the bacterial host genome?
prophage
toxins of the bacteria responsible for diphtheria, cholera, and botulism are produced by:
prophages
capsomers are composed of (macromolecule)
protein
viral spikes are composed of ____
proteins
a ____ is an animal virus which has integrated its DNA into the DNA of its host cell
provirus
in which stage of viral multiplication would you expect to see "budding" occur
release
this image illustrates the ___ step in the bacteriophage life cycle?
release -bacteria falling out of the cell
in which of the following ways enveloped animal viruses released from the host cell?
release from the ER and bud off the cell membrane
a noncellular infectious agent that depends on other viruses for replication is known as a ______ virus
satellite
when individual viral genes exist on separate pieces of genomic RNA the genome is said to be ______
segmented
Some laboratory animals can propagate viruses in the laboratory more readily than others because many viruses exhibit host ______
specificity
viral ______ insert into the host cell membrane as the virus particle is assembled in the host cell
spikes
Identify all the types of nucleic acid genomes which have been discovered carried by various bacteriophages
ssRNA ssDNA dsDNA
unlike cellular organisms, viruses are unable to
synthesize their own proteins
the human virome is
the complete set of viruses associated with the human body
viral transformation by oncogenic viruses implies
the host cell is changed
change in a cell line monolayer is indicative of which of the following
virally infected cells
a fully formed infectious virus particle in a host cell is often called a
virion
a type of virus that parasitizes other viruses infecting the same host cell is called a
virophage
identify the smallest pathogenic agent
virus
which of the following is true?
viruses are not cellular
which of the following is a true statement
viruses are smaller than yeast cells
Which facts best supports the position that viruses are not living organisms?
viruses do not have any means of independent metabolism and cannot reproduce on their own
the smallest virus is about what size?
20 nanometers
the initials ____ are used for cytopathic effect
CPE
identify any of the following pathways which could produce proteins by viruses
Host DNA> mRNA viral positive-ssRNA
which of the following statements about treating viral diseases are correct
antibiotics are not effective against viruses and most vaccines target viral diseases
Identify any of the following which viroids do NOT have.
capsid metabolic pathways mitochondrion envelope
what are the three main criteria used to classify viruses
chemical composition structure genetic makeup
where are most RNA viruses replicated and assembled within the host
cytoplasm
most bacteriophages have ______-stranded DNA genomes
double
viruses can cause cancer by
introducing oncogenes to a host cell and causing a loss of growth regulation
Typically, naked helical viruses are _____ flexible than enveloped helical viruses. Less More
less
which term refers to the physical rupture of a cell
lysis
the word virus comes from the latin word for _____
posion
which type of phage generally increases the pathogenicity of a bacterium
temperate phage
true or false: most viral infections do not result in death of the host organism
true
which step in the life cycle of an animal virus is not needed in the cycle of a bacteriophage
uncoating
viruses with a ___________ capsid have rod-shaped capsomers, while the capsomers of viruses with ___________ capsids are arranged as a multifaceted polygon
helical iscosahedral
lysogen is best described as
integration of the viral genome into the host chromosome
Capsids of _______ helical viruses are rigid and tight, while capsids of _______ helical viruses are flexible and loose
naked enveloped
identify the virus types which are released from host cells by lysis
naked, complex
in ______ sense RNA viral genomes, the RNA is not in a form ready for translation
negative
at minimum, all viruses are composed of:
nucleic acids and proteins
viruses have tropisms, that is they can infect....
only cells of a certain tissue type
identify the commonalities between temperate phages and lytic phages
penetration, release, adsorption, assembly, biosynthesis of viral components
when a cell harbors a virus that is not immediately lysing the cell, its known as what type of infection?
persistent infection
single stranded RNA genomes that are ready for immediate translation into proteins are called ______ RNA
postive-sense
a(n) _____ is an infectious agent made up of only protein and associated with spongiform encephalopathies
prion
the virus buds off the membrane and picks up an envelope and spikes in the _____ stage of the viral life cycle
release
in some viruses, including HIV, the enzyme ___________ ___________ transcribes RNA into DNA
reverse transcriptase
the enzyme ____ ____ is a preformed protein carried in by HIV responsible for converting its RNA genome into DNA
reverse transcriptase
viral glycoproteins that protrude from the viral envelope and attach to host cell receptors are termed _____
spikes
bovine ____ encephalopathy, or "mad cow disease" is a disease condition of the brain caused by an infection with prions
spongiform
_____ occur when a virus induces multiple cells to fuse, making a large multinucleated cell
syncytia
Some deadly human pathogens such as diphtheria, cholera, and botulism are made more virulent by bacteriophages known as ____ phages, or prophages
temperate
____ pages do not immediately lyse or change the appearance of host cells/
temperate
a _____ phage is a bacteriophage that incorporates itself into the host genome as a lysogenic prophage.
temperate
the process of ____ occurs when viruses lose their capsid (and envelope if they have one) during or after penetration into a host cell?
uncoating
Estimated, there are several billion cases of _____ infections each year in the world.
viral
it is challenging for scientists to design antiviral drugs because
viruses use host features for their life cycle so many drugs would affect host cells
lysogenic conversion is when
a bacterium acquires a new trait from its temperate phage
which of the following best describes a prion
abnormal protein fibrils
viruses are best described as ___ rather than alive
active
_____ is the viral process of attaching to the host cell receptor for the virus
adsorption
list the correct order of viral life cycle phases
adsorption, penetration, uncoating, synthesis, assembly, release
exocytosis, or _________ of enveloped viruses occurs from the host cell membrane during the release stage of the viral multiplication cycle.
budding
mature enveloped viruses are released from host cells via ____ or exocytosis
budding
two ways in which newly assembled viruses are released from host cells are through ______ or exocytosis by enveloped viruses, and through _____ (rupture) by naked viruses
budding lysis
which is closes in physical proximity to the nucleic acid of a virus
capsid
which structure immediately encloses viral nucleic acid
capsid
viruses have fewer genes than bacteria because
they only need to redirect a cell's activity
cell culture and _____ culture have the same meaning
tissue
list three purposed of viral cultivation
to prepare vaccines to study effects on host cells to identify viruses in clinical specimans
which of the following is considered a monomer of a capsid?
capsomere
most RNA viruses will assemble the virionn within the host cell's _______.
cytoplasm
chicken -____ have a monolayer of cells within them which offers good place to propagate virus
eggs
