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