MIC 205 learnsmart: viruses
a viroid is composed only of
RNA
viroids are composed of naked ________ strands
RNA
T/F: "transduction" has been linked to the spread of antibiotic resistance in bacteria
T
T/F: all viruses must infect a host cell in order to replicate
T
T/F: genes for toxin production can be transferred between bacteria via transduction by viruses
T
T/F: most active viral infections lead to cell death regardless of the type of release process
T
T/F: most enveloped viruses are animal viruses
T
T/F: most viruses are smaller than .2 microns
T
T/F: viral nucleic acid may be single-stranded or double-stranded DNA or RNA
T
T/F: viruses can be both harmful or beneficial to humans
T
T/F: viruses can't be called organisms
T
viruses that specifically infect the bacterium E. coli are known as
T-even phages
the various viral "parts" coming together to produce virions
assembly
any virus that specifically infects bacteria
bacteriophage
viruses _______ depend on a host cell for replication
completely
describes viruses which have a non-icosahedral or non-helical arrangement of capsomer proteins
complex
which type of capsids are composed of multiple protein types and nonsymmetrical shapes
complex
bovine
cow
which disease is associated with prions
creutzfeldt-jacob disease (CJD)
acronym CPE stands for
cytopathic effects
most RNA viruses will assemble the virion within the host cell's ______
cytoplasm
bacteria that can't reproduce
dead
most bacteriophages have _______-stranded DNA genomes
double
viral nucleic acids are
either single-stranded or double stranded
capsids of _____ helical viruses are flexible and loose
enveloped
an ________ virus has a membranous layer external to nucleocapsid
enveloped virus
what are the viral spikes typically composed of
glycoproteins
viruses which have a series of capsomer proteins linked together forming a barrel
helical
viruses that have rod-shaped capsomers
helical viruses
family name of the HSV-1
herpesviridae
viral transformation implies
host DNA is changed
term used to describe the different host cells which a virus can infect
host range
different viruses can infect which of the following
human, bacterial, or plant cells
capsid structure which has 20 panels of capsomers arranged in a symmetrical pattern
icosahedral
the capsid of a virus which has 20 equally spaced panels of capsomers forming a symmetrical structure
icosahedral
viruses that have multifaceted polygon capsomers
icosahedral viruses
a geometric viral form having 20 faces and 12 corners
icosahedron
viruses that can't reproduce
inactive
________ bodies are masses of viruses or damaged organelles of a cell due to a cytopathic effect of viral infection
inclusion
through the process of ________, a prophage is activated and enters the lytic cycle
induction
nonliving microscopic agent
infectious particle
how does bacteriophage nucleic acid enter the host cell
injection
physical rupture of a cell
lysis
viral bursting of any host cell
lysis
when a bacterium acquires a new trait from a temperate phage, _______ conversion has occured
lysogenic
a bacteriophage-mediated process by which bacteria gain genes enhancing their ability to cause human disease
lysogenic conversion
process by which bacteriophages infect bacteria, conferring new traits enhancing human disease
lysogenic conversion
integration of the viral genome into the host chromosome
lysogeny
the persistence of bacteriophages within host cells
lysogeny
capsids of _________ helical viruses are rigid and tight
naked
virus that doesn't have an envelope surrounding its capsid
naked virus
which unit best describes viruses
nanometer
in _________ RNA viral genomes, the RNA isn't in a form ready for translation
negative-sense
if the primary "purpose" of the viral capsid and envelope is the protection of viral nucleic acids, what are they protecting form
nucleic acid degrading compounds
where are most DNA viruses replicated and assembled within the host
nucleus
best describe viruses as
obligate intracellular parasites
________ viruses lead to cancer in infected hosts
oncogenic
any virus that can lead to cancer
oncovirus
cell harboring a virus that isn't causing cytopathic effects is characteristic of which type of infection
persistent infection
infections where cells are infected yet show no cytopathic effects
persistent infections
process that occurs when viruses are taken into the cell followed by engulfment in a vacuole or vesicle
phagocytosis
the viral envelope is composed of
phospholipids
disease-causing agent composed only of protein
prion
what isn't a function of the viral capsid/envelope
production of viral protein in the host
bacteriophages can infect which of the following
prokaryotes only
phage DNA that is latently incorporated into the bacterial host genome
prophage
primary function of the viral capsid and envelope
protection
which macromolecule composes capsomers
proteins
an animal virus that has integrated its genome into the host cell's genome
provirus
in which stage of viral multiplication would you expect to see budding occur
release
viral exocytosis
release
HIV is describes as a ________ because it synthesizes DNA from RNA using reverse transcription
retrovirus
______ _____ is a preformed viral enzyme that synthesizes the nucleic acid DNA from the nucleic acid RNA
reverse transcriptase
a preformed protein carried in by HIV responsible for converting its RNA genome into DNA
reverse transcriptase
an enzyme capable of taking an RNA genome and generating a DNA copy is called
reverse transcriptase
noncellular infectious form that depends on other viruses for replication
satellite virus
genus of Herpes simplex 1 virus
simplexvirus
which of the following viral structures must be specific for adsorption
spike proteins
most viral ______ in the capsid or envelope are composed of glycoproteins
spikes
viral proteins which protrude from the envelope and aid in attachment to host receptors
spikes
a helical capsid has a ______ shape
spiral
occurs when a virus induces multiple cells to fuse making a large multinucleated cell
syncytium
name given to a phage "type" which can incorporate itself into the host genome as a lysogenic prophage
temperate
which type of phage generally can increase the pathogenicity of a bacterium
temperate phage
process that occurs when viruses lose their envelope during penetration into a host cell or when the envelope/capsid is/are dissolved within a vacuole
uncoating
there are several billion cases of ______ infections each year in the world
viral
single virus particle
virion
infectious agent that lacks a capsid and merely consists of a strand of RNA
viroid
what is completely composed of RNA
viroid
a microscopic, acellular agent composed of nucleic acid surrounded by a protein coat
virus
obligate (in regards to viruses)
viruses must have a host cell
is it possible for bacterial cell infected with a temperate phage to replicate
yes
prion related diseases
1. Creutzfeldt-Jakob disease 2. Bovine spongiform encephalopathy
pathways which could produce proteins used by viruses
1. Host DNA --> mRNA --> proteins used by viruses 2. Viral positive ssRNA --> proteins used by viruses
functions of viral capsid/envelope
1. adherence to host cells 2. assisting penetration of viral nucleic acid into host cell
what functions are reliant on the viral capsid
1. adsorption 2. penetration
order of viral life cycle
1. adsorption 2. penetration/ uncoating 3. synthesis 4. assembly 5. release
different environments in which some viruses can replicate
1. bacterial cells 2. human cells 3. animal cells
commonalities between temperate phages and lytic phages
1. biosynthesis of viral components 2. penetration 3. adsorption 4. release 5. assembly
viral structures that can promote binding to a host cell
1. capsid 2. envelope
all components of the nucleocapsid
1. capsid 2. nucleic acid
components of nucleocapsid
1. capsid 2. nucleic acid
a single vitrion could contain a genome of
1. dna only 2. rna only
methods that a virus can use to gain entry into an animal cell
1. fusion of viral envelope and cell membrane 2. engulfment/ phagocytosis of virus
2 shapes of capsids
1. helical 2. icosahedral (type of polyhedron)
cytopathic effects in virally infected animal cells
1. inclusions 2. syncytia 3. giant cells
what do viroids not have
1. metabolic pathways 2. mitochondrion 3. envelope 4. capsid
examples of cytopathic effects
1. multinucleated cells 2. giant cells 3. inclusion bodies
identify the virus types which are released from host cells by lysis
1. naked 2. complex
at a minimum, all viruses are composed of
1. nucleic acids 2. proteins
what is reliant on the viral capsid
1. penetration 2. adsorption
benefits of viruses to people
1. some viruses control food pathogens 2. some viruses can be modified to deliver genetic cures 3. some viruses control insect pests
types of nucleic acid genomes which have been discovered carried by various bacteriophages
1. ssDNA 2. dsDNA 3. dsRNA 4. ssRNA
2 main criteria used in classifying viruses into families
1. structure 2. genetic makeup
organisms smallest to largest
1. viruses 2. bacteria 3. human cells
what facts best support the position that viruses aren't living organisms
1. viruses can't reproduce on their own 2. viruses don't have any means of independent metabolism
T/F the viral envelope and capsid are the same thing
F
T/F: all noncellular infectious agents are morphologically similar to viruses
F
T/F: the capsid of all viruses is protected by an external envelope
F
T/F: viral spikes insert into the host cell membrane as the virion is released from the cell
F
viral process of attaching to the host cell receptor of the virus
adsorption
in describing the release of mature enveloped viruses from host cells, the terms exocytosis and ____________ are interchangeable
budding
viral release methods that won't initially destroy the cell
budding
two ways in which newly assembled viruses are released from host cells are through ___________ or exocytosis by enveloped viruses, and through _________ by naked viruses
budding; lysis
closest in physical proximity to the nucleic acid of a virus
capsid
the structure directly surrounding the viral nucleic acid is the _____, a coat of proteins
capsid
monomer of a capsid
capsomer
protein subunit that forms the viral capsid
capsomer
capsid is composed of
capsomer proteins
total nucleic acid content of a virus can be referred to as
the viral genome
human bacteria that are lysogenized with phage may produce ______ that are harmful to the host
toxins
genes for drug resistance can be transferred between bacteria via bacteriophages during the process of
transduction
process where a virus transfers bacterial genes from another bacterial cell to another
transduction
when a phage transfers genes between bacteria
transduction
