question

Tabacco mosaic virus can be transmitted from a dieseased plant to a

answer

healthy plant

question

the first human disease associated with a filterable agent was

answer

yellow fever

question

virus is the latin word for

answer

poison

question

the invention of what made it possible to see viruses

answer

the electron microscope

question

Viruses are inert when they are living .. and active when they are living ..

answer

outside the cell.. inside the cell

question

what are two ways viruses are distinguished from other infectious agents

answer

1. they are small and filterable
2. obligatory intracellular parasites
3. their methods of multiplication
and their simple structure

question

viruses are entities that :

answer

1.contain a single type of nucleic acid either DNA or RNA
2.contain a protein coat ( somtimes covered by an envelope) that surrounds a nucleic acid
3. multiply inside living cells by using the synthesizing machinery of the cell
4. cause the synthesis of specialized structures that can carry the viral nucleic acid to other cells

2.

question

viruses have few or no enzymes of their own for metabolism

answer

true

question

viruses have their own enzymes for protein synthesis and ATP generations

answer

false , they are completly and entirely dependant upon their host

question

does viruses repicate by binary fisson

answer

no

question

does viruses both RNA and DNA

answer

no

question

viruses are sensative to antibiotics

answer

true

question

are viruses sensative to interferons

answer

yes

question

why can the effect of antiviral drugs be dangerous to us?

answer

because most drugs that interfere with viral replication would also interfer with the functioning of the host cell

question

host range of a virus

answer

is the variety of host cells the virus can infect

question

true or false : most viruses are able to infect specific tyoes of only one host species

answer

true

question

viruses that infect bacteria are called

answer

bacteriophages, or phages

question

what is the particular host range of a virus determines by?

answer

the viruses requirements for its specific attachment site, and the availablitly within the potential host of cellular factors required for viral reproduction

question

in animal cell the receptor sites are on the

answer

the plasma membrane

question

for some bacteriopgahes the receptor site is part of the cell wall, in other cases it is apart of the

answer

fimbriae, or flagella

question

phage therapy

answer

the idea of using bacteriphages to treat bacterial infection

question

onolytic viruses

answer

tumor-destroying , may selectively infect or kill tumor cells or cause an immune response towards them

question

different viruses are all the same size?

answer

false they vary considerably in size

question

all viruses are way smaller than bacteria?

answer

false although most are smaller than bacteria some of the larger viruses ( such as vaccinia virus) are about the same size as some very small bacteria ( mycoplasmas,rickettias,chlamydias)

question

viruses range from .... in lengthq

answer

20 to 1000 nm in length

question

sometimes influenza A viruses seen in one species can cross over to another species

answer

true

question

influenza has many different subtypes of influenza differ because of the

answer

different proteins on the surface of the virus

question

what are the three known subtypes of human influenza virus?

answer

H1N1,H1N2,H3N2

question

why are pigs important carriers of the influenza virus

answer

because they can be infected with both human and avian flu

question

influenza virus is composed of

answer

eight seperate segments, which allows the virus to mix and create a new influenze virus, knwon as antigenic shift

question

virion

answer

a complete, fully developed infectious particle of nucleic acid surrounded by a protein coat that is protected from the enviroment and is a vehicle of transmission from one host cell to another

question

viruse are classified by what

answer

the different structure of their protein coat

question

the nucleic acid of a virus can be

answer

double stranded or single stranded
( double stranded, DNA, double strsnded RNA, single stranded RNA, single stranded DNA)

question

depending on the virus the nucleic acid can also be

answer

linear or circular

question

in some viruses such as the influenza virus the nucleic acid is in several segments

answer

true

question

the nucleic acid in a virus is protected by the protein coat called

answer

capsid

question

the structure of the capsid is ultimitely determined by

answer

the viral nucleic acid

question

what takes up the most mass of the virus

answer

the capsid

question

somtimes there might be a single protein subunits that compose the capsomere and sometimes several types of protein are presentq

answer

true

question

what does an envelope consist of

answer

lipids, proteins, carbohydrates

question

some animal viruses are released from the host cell by an extrusion process that encoats the virus with a layer of the hosts cells plasma membrane , which becomes the

answer

viral envelope

question

enveloped viruses are always convered in spikes

answer

false, depending on the virus enveloped viruses may or may not be covered in spikes

question

spikes

answer

carbohydrate- protein complexes that project from the surface of the envelope

question

can spikes be used as identification?

answer

yes

question

some viruses attach to host cells by means of spikes?

answer

true

question

hemagglulation

answer

spikes cling to red blood cells causing clumping

question

what does the capid of nonenveloped viruses protect the viruse from

answer

nuclease enzymes in biological fluids and promotes the viruses attachment to suseptable host cells

question

Antibodies

answer

proteins that react with the surface proteins of viruses, they should inactivate the virus and stop the process

question

what does the cell send out as an immune responce to a virus

answer

antibodies

question

how can viruses escape antibodies?

answer

because regions of the gene that code for the viruses surface proteins are suseptable to mutation, then the antibodies are not able to deactivate the virus

question

influenza constanly undergoes mutation in its spikes that is why we can get it twice

answer

true

question

the viruse that cause rabies and ebola hemorraphagic fever are what type of general morphology

answer

helical viruses

question

name two polyhedral viruses

answer

polio virus, and adrenovirus

question

envelope viruses are roughly what shape

answer

spherical

question

an example of a enveloped polyhedral virus

answer

is herpes simplex virus

question

what is one example of a complex virus

answer

bacteriaphage

question

the head of a bacteriophage is what shape and the tail is what shape

answer

polyhedral and the tail heath is heical

question

what is another example of a complex virus

answer

poxvirus

question

the oldest classification of viruses is based on

answer

symptomology, this didnt work because some viruses had more than one effect on its host

question

viruses grouped by

answer

1. nucleic acid type
2. statagy for replication
3. morphology

question

viral species

answer

a group of viruses that share the same genetic information and geological niche ( host range)

question

viral species are designed by descriptive viral names

answer

true

question

viruses that use what as hosts are easily grown on bacterial cultures

answer

bacterial cells

question

alot of understanding of viral replication is dedicated to

answer

bacteriophages

question

the plague method for detecting coutable viruses

answer

the viruses are cultured on a bacterial plate the viruses attack the bacteria and the area surrounding where the original bacteria was is destroyed. this produces a number of clearings that we can count to determine the viral number.( plague forming units)

question

what three methods are used for cultivating animal viruses

answer

1. living animals
2. embryonated eggs
3. or cell cultures

question

some human viruses can not be grown in animals, or can be grown just not cause disease

answer

true

question

we watch viral reproduction of AIDS in which animal? but we can not provide vaccine models):

answer

mice

question

if the virus can grow in a embryonic egg

answer

a hole is drilled in the shell, and a virus is injected into the fluid of the egg

question

how is viral death indicated in an embryonic egg

answer

death of the embryo, by embryo cell damage, or the formation of pockets or cell lesions on egg membrane

question

cell culture

answer

is the preferred type of growth medium for most organisms

question

cytopathic effect

answer

viruses that infect to monolayer cause the cells of the monolayer to deteriate as they multiply

question

viruses can be grown in --- or --- lines

answer

primary or continuous

question

diploid cell lines

answer

developed from human embryos and can be maintained for about 100 generations and are widely used for cultivating viruses used in human hosts

question

the major problem with the cell culture method

answer

is the cells can not be contaminated , required the full time attention of workers

question

serological method such as western blotting

answer

the virus is detected by its reaction to antibodies most common method of identification

question

what genes do the nucleic acid in a virion contain information for

answer

1. to make capsid protein
2. and genes for a few enzymes used in viral life cycle

question

viral enzymes are almost entirely concerned with replicating or processing what

answer

viral nucleic acid

question

the larger virions may contain one or a few enzymes whcih usually function in helping the virus penetrate the host cell or replication or replicating its own nucleic acid

answer

true

question

the multiplication of a virus can be demonstrated with a

answer

one step growth curve

question

a one step growth curve

answer

the data is obtained from infecting every cell in a culture and then testing the culture medium and cells from virions and viral proteins/ nucleic acids

question

bactreiophages can multiple by which teo alternative mechanisms

answer

the lytic cycle ( ends with the life and the death of the cell)
,and the lysogenic cycle( the host cell remains alive)

question

what organism is an example of the lytic cycle

answer

e. coli

question

the virions of a T-even bacteriophage are

answer

large, complex, and nonenveloped, with a characteristic head and tail shape

question

the lytic cycle attachment phase with T-even bacteriophages

answer

a chance of collision occurs, attachment site on a bacteriophage ( fibers at the end of its tail) attaches to a complementary receptor site on a bacterial cell wall, weak bond formed ( hydrogen bond)

question

penetration of the T-even bacteriophage

answer

injects its DNA ( nucleic acid) into the bacterium, the tail sheath of the bacterialphage contracts anf the tail core is driven into through the cell wall. ( like a syringe)

question

phage lysosome

answer

released by the bacteriophage to break down a portion of the cell wall during penetration to allow the DNA to be injected into the cell

question

once the bacteriophage DNA has reached the ---- of the host cell the biosyntheis of viral nucleic acid and protein occurs

answer

cytoplasm

question

the virus cuts off the host DNA reproduction by

answer

shutting off the transciption and translation

question

what is the order of Virus transcribed?

answer

1. copys phage cells DNA
2. phage DNA is transcribed into mRNA in order to make capsid proteins

question

early phage messages are translated to early phage proteins during biosynthesis which are used for

answer

the synthesis of phage DNA

question

late messages are translated into late phage proteins for the synthesis of

answer

capsid proteins

question

for several minutes following infection, complete phages can not be found in the host cell only seperate components DNA and protein can be detected this is called the

answer

eclipse period

question

during muturation DNA and capsids are assembled into virions spontaneously

answer

true

question

bacteriophage lambda is also called

answer

lysogenic cycle

question

lysogenic phages are also called

answer

temperate phages

question

temperate phages may indeed proceed through the lytic cycle but they are also able to incorporating their DNA into the host cells DNA to begin a lysogenic cycle.

answer

true

question

in lysogeny the phage remains

answer

latent (inactive)

question

the steps to lysogency

answer

after penetration the linear phage DNA forms a circle
the circle can multiply and divide
leading to the production of new phages and the lytic cycle

question

the inert DNA in the lysogenic cycle is called the

answer

prophage, most of the phage genes are turned off by repressor proteins, these stop transcription

question

everytime the host cells machinery replicates during the temperate phage the

answer

bacterial chromosome replicates the prophage DNA the prophage remains latent with in the progeny cells

question

when the cell is in the temperate phage what can cause the phage DNA to spontaneously leave the cell the lytic cycle

answer

action of uv light, certain chemicals

question

3 important results of lysogeny

answer

1. the lysogenic cells are immune to reinfection by the same phage ( however the host cell is not immune to infection ).
The host cell might experience phage conversion

question

phage conversion

answer

the host cell exhibits new properties

question

the third result of lysogency is that it

answer

makes specialized transduction possible ( only certain genes are transferred) phage coat picks up bacterial genes and transfers

question

specialized transduction

answer

is mediated by the lysogenic phage, which packages bacterial DNA along with its own DNA in the same capsid

question

how do animal viruses differ from bacterial virus?

answer

the way they enter the cell
the synthesised cell particles are different because of prokaryotic and eukaryotic cells are different
also animal cells have different enzymes
the mechanism of maturation and release is different

question

what are the receptor cites for animal cells

answer

proteins, glycoprotein of the plasma membrane

question

animal viruses do possess appendages like tail fibers

answer

false, the attachment site for animal viruses is dispersed over the surface of the cell

question

the spikes are located on the

answer

envelope of the virus

question

attachment is complete when

answer

many sites are bound

question

recepeptor sites are or are not inherited by the host?

answer

are, so the receptors for a particular virus can very from host to host so some people are not suseptable to viruses

question

viruses and other nutrients / molecules can enter eukaryotic cells by an active cellular process called

answer

pinocytosis

question

pinocytosis

answer

the plasma membrane has many continuous folds that contain digestive enzymes

question

what kind of viruses can enter by fusion, in which the viral envelope fuses with the plasma membrane and released the capsid into the cells cytoplasm

answer

eneveloped virus

question

uncoating

answer

this happens with animal viruses its the seperation of the viral nucleic acid from the protein coat once the virion is inside the vesicle

question

uncoating is the action of what type of enzymes

answer

lysosomal enzymes, enzymes in the hosts cytoplasm

question

how do animal cell viruses enter the cell

answer

by endocytosis or fusion

question

in bacteriophages where does biosynthesis occue

answer

in the cytoplasm

question

in animal viruses where does biosynthesis occur

answer

in the nucleus ( DNA viruses) in the cytoplasm ( RNA viruses)

question

in animal viruses how are viruses released

answer

enveloped viruses budout, nonenveloped viruses rupture the cellq

question

chronic infection in animal cells is known as

answer

latency - slow infection

question

is uncoating required in bacteriophages

answer

no

question

DNA containing viruses replicate their DNA in the --- and they synthesis their capsid in the ---by using host cell enzymes

answer

nucleus , cytoplasm

question

after the DNA containing viruses are assembled they are transported along the what to be released outside the cell

answer

endoplasmic reticulum

question

what DNA containing viruses are an exception because they synthesis all their materials in the cytoplasm

answer

poxviruses

question

does poxvirus contain its own transcriptase thats why all the replication happens outside the nucleus

answer

true

question

adrenoviruses were names after adenoids

answer

true

question

adrenoviruses cause what

answer

respiratory disease the common cold

question

poxviridea diseases include

answer

small pox, cow pox, skin lesions

question

pox refers to

answer

a pus filled lesion

question

hepadnaviridae uses they synthesis DNA by using RNA.. KNOWN AS

answer

reverse transcriptase

question

retroviruses use

answer

reverse transcriptase

question

does budding kill the host cell

answer

no and in some cases the host cell survvies

question

alot of cancer is a result of viruses

answer

true

question

wilhelm ellerman and olaf bang

answer

are responsible for finding that leukemia in chickens is caused by virsus

question

peyton rous

answer

discovered that tumors in chickens were caused by viruses saracoma!

question

cancer has to develope right away

answer

false, cancer might not develope until long after viral infection

question

is cancer contagious

answer

no

question

almost anything that cn alter the genetic material of a eukaryotic cell can cause cancer

answer

true

question

the cancer - causing alterations to cellular DNA affect parts of the genome called

answer

oncogenes

question

oncogenes can be actives by

answer

mutagenic chemicals, high ebergy radiation, viruses

question

viruses capable of inducing tumors are called

answer

oncogenic viruses, cellular DNA integrates into the host DNA and replicates along with the host cells chromosome

question

what percent of cancer is known to be viral induced

answer

10%,

question

tumor cells are --- by viruses they aquire distinct properties different from noninfected cells

answer

transformation

question

is a oncogenic virus a DNA or RNA virus

answer

DNA

question

virtually all cervical cancers are caused by

answer

human papallomarvirus HPV

question

does hepatitus virus cause cancer

answer

true

question

among the RNA viruses only the oncoviruses in the family --- cause cancer

answer

retroviridae

question

are saracoma viruses of cats chickens and rodents also retroviruses

answer

yes

question

provirus

answer

The product of a reverse transcription whcih is the double stranded DNA molecule synthesised from viral DNA which integrates into the host cell DNA

question

latent infection

answer

question

latent infection

answer

a virus can remain in equilibrium with the host and not actually produce disease for a long time , often many years.

question

the herpes virus is an example of a

answer

latent virus

question

can chicken pox exist in a latent stage

answer

yes, the virus contains access to the skin via the blood some viruses may enter the nerves where they remain latent

question

when chickenpox is latent and activated by a immune responce can active them and change them to

answer

shingles

question

shingles occur in what to what percent of people who have had chickenpox

answer

10-20%

question

persistant or chronic infection

answer

occurs gradually over a long period, usually are fatal

question

a persistant viral infection is different from a latent infection is that it

answer

detectable viruses build up over a long period of time and rather than appearing suddenly

question

are infectious diseases caused by prions

answer

yes

question

what disease is caused by prions

answer

scrapes

question

the infectivity of scrapies infected brain tissue is reduced by treatment with --- but not by treatment with --- this suggests the infecting agent is pure ---

answer

protease, radiation, pur protein

question

prion is a named coined from

answer

protinaceous infectious particle

question

prion cause mad cow disease?`

answer

true

question

can some plant viruses multiply in animal hosts?

answer

yes

question

what kind of change can plant viruses cause

answer

color change wilting. deformed / stunted growth

question

some plant viruses are only resevoirs and remain latent

answer

true

question

how are plant cells protected from disease

answer

their cell wall

question

plant viruses can only enter via

answer

wounds, or assisted by other plant parasites, nemotodes, fungi, and animals that suck sap

question

how is plant diease spread

answer

by pollen and seed

question

in laboratories plant viruses are cultured in

answer

protoplasts plant cells with their cell wall removed

question

some plant diseases can be caused by short pieces of naked DNA only 300-400 nucleotides with no protein coat called

answer

viriods

question

does the RNA in viriods code for any proteins

answer

no

question

are viriods pathogens only for plants

answer

yes

question

annually infections by viriods result in alot of crop damage for example

answer

potatoe spindle tuber viriod

question

do viriods and introns have a similar base sequence?

answer

yes ( a sequence of genetic material that do not code for polypeptides)

question

viriods have evolved from introns

answer

true its thought to be

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