Micro ch.5 viral structure and multiplication

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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


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