Micro 301 Chapter 11

Consequences of lysogeny include _______ - morphological changes - lysogenic conversion - immunity to superinfection - phage induction and conversion

lysogenic conversion and immunity to superinfection

animal Viruses can be studied by infecting ____ - E. coli cells - fertilized chicken eggs - cell or tissue culture - live animals

- fertilized chicken cells - cell or tissue cultures - live animals

The major categories of animal viral infections are ____ infections, characterized by the sudden onset of symptoms of a relatively short duration, and ___ infections that can continue with or without symptoms for years.

Acute; persistent

The basic parts of a bacteriophage are - a helical capsid, envelope, tail pins, and spikes - a tail, envelope, tail pins, and fibers - a helical capsid, envelope, and spikes - an icosahedral capsid, envelope and tail - an isohedral head, tail pins, and fibers

An isohedral head, tail pins, and fibers

Which of the following directs the incorporation of phage DNA into a bacterial chromosome? - gyrase - isomerase - lysozyme - polymerase - integrase

Integrase

Both enveloped and non-enveloped (naked) viruses can enter a cell by endocytosis - true - false

True

Viral spikes - attach specifically to host cell receptors - attach non-specifically to host cell receptors - are composed of polysaccharides - are made of lipids - are present in all viruses

Attach specifically to host cell receptors

Which viral stage occurs first? - release - assembly - uncoating - penetration - synthesis - attachment

Attachment

which type of viruses are released by budding? - RNA viruses - Enveloped viruses - non-enveloped viruses - DNA viruses

Enveloped Viruses

True of False: Enveloped and non-enveloped virus all mature fully in the cytoplasm of the host cell.

False

______ is a change in the phenotype of a lysogen as a consequence of the specific prophage it carries. - Latency conversion - lysogenic cycle - lysogenic conversion

Lysogenic Conversion

Productive Infection

New viral particles are produced

In a(n) ____ assay, the clumping of red blood cells is used to determine viral titer. - hemagglutination - quantal - ames test - plaque

hemagglutination

In which type of infection does the virus remain in the host for years, sometimes without symptoms? - acute - primary - persistent - secondary

Persistent

Which of the following proteins is essential for maintenance of the lysogenic state? - Activator - Integrase - Lysozyme - Isomerase - Repressor

Repressor

Viruses that have an RNA genome and use reverse transcriptase to synthesize a DNA copy of that genome are called _____ - auto viruses - retroviruses - reverse viruses - viroids

Retroviruses

In _____ transduction, only bacterial genes adjacent to the prophage can be transferred; whereas in _____ transduction, any bacterial gene can be transferred.

Specialized; generalized

Latent state

Viral genome remains silent within the cell

More than one mechanism of viral entry into a host cell exists - true - false

True

In a quantal assay, LD50 is the amount of pathogen that _____ - infects half of a test population - kills all of a test population - infects all of a test population - kills half of a test population

kills half of a test population

one of the early proteins expressed in the T4 lytic cycles is an enzyme called a ____ that degrades the bacterial DNA

nuclease

What term describes the type of bactiophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide? - oncogenic - lytic - hemorrhagic - lysogenic

Lysogenic

When present, of what is the viral envelope composed? - carbohydrates - mainly protein - proteins and sugars - mainly lipids - nucleic acid

Mainly lipids

Bacteriophages adsorb or attach - only to members of the same bacterial species - only to members of the archaea - non-specifalcly to bacterial cells - to plant and animal cells - only to members of the same family

Only to members of the same bacterial species

In transduction, bacterial DNA is transferred to a new cell when - the virus is brought into the host by endocytosis - it is injected by the virus - it binds to a receptor on the bacterial cell wall - something triggers the host to produce new DNA - it binds to a receptor on the host cytoplasmic membrane

it is injected by the virus

Some pathogenic bacteria produce toxins that are encoded on prophage DNA, and these are examples of ____ conversion

- lysogenic

Which of the following methods can be used to quantify animal viruses? - quantal assay - plaque assay - hemagglutination - direct count - biuret assay - ames test

- quantal assay - plaque assay - hemagglutination

During maturation or formation of phage particles - viral DNA is wrapped in an endocytic vesicle and released - a few phage heads may surround fragments of host bacterial DNA - single strands of bacterial and viral DNA hybridize - chromosomal fragments start to reassemble - the host nuclear membrane reforms

- a few phage heads may surround fragments of host bacterial DNA

When cultivated in flasks, human cells from solid tissues ____ - adhere to the bottom of the surface (substrate) - form multi-layered, tumor-like masses - grow in suspension - grow as a monolayer

- adhere to the bottom of the surface - grow as a monolayer

Regarding animal viruses, which of the following statements are true? - blocking a host receptor with a drug would prevent a virus from infecting that cell - the normal function of host membrane receptors is for virus adsorption - viruses use their spikes to attach to host cell receptors - some viruses require more than one host cell receptor for attachment

- blocking a host receptor with a drug would prevent a virus from infecting that cell - viruses use their spikes to attach to host cell receptors - some viruses require more than one host receptor for attachment

Generalized transduction occurs when - specific bacterial genes are replicated by bacteriophage - specific bacterial genes are dented by a bacteriophage - a bacterial cell packages a piece of viral DNA during replication - DNA passes from one bacterial cell to another by a sex pilus - a bacteriophage packages a piece of bacterial DNA during replication

A bacteriophage packages a piece of bacterial DNA during replication

Viruses that infect bacterial cells are called ___ - viroids - toxins - bacteriviri - bacteriophages bacteriocins

Bacteriophages

In animal virus replication, an uncoating step is needed to release the nucleic acid from the capsid. Why is this step not needed in bacteriophage replication? - bacteriophage only contain RNA - uncoating is also needed in the phage life cycle - bacteriophage inject their DNA into the host cell - bacteriophage do not replicate - bacteriophages only contain protein and lipids

Bacteriophages inject their DNA into the host cell

A positive (+) strand of RNA - makes a minus (-) strand of RNA, which can then act as mRNA - must be converted back to DNA for gene expression - can directly act as mRNA - must be double-stranded

Can directly act as mRNA

When the bacteriophage transfers bacterial DNA into a recipient bacterial cell, this DNA - triggers the formation of an endospore - circularizes and forms a plasmid - lyses the bacterial host immediately - can integrate into the chromosome - hybridizes with RNA present in the cell

Can integrate into the chromosome

Choose the term that describes a virus that has a lipid bilayer (derived from the host cell) surrounding its capsid - icosahedral virus - non-enveloped (naked) virus - enveloped virus - coated virus

Enveloped Virus

All viruses can infect any cell type or tissue type - true - false

False

Viral capsids are composed of _____ - phosphates - lipids - nucleic acids - carbohydrates - protein

Protein

Replicases are _____ polymerases - DNA dependent DNA - RNA dependent DNA - RNA dependent RNA - DNA dependent RNA

RNA dependent RNA

During viral infection of a host cell, which is the third step of the process? - attachment to host cell - release of nucleocapsid into host cytoplasm - biosynthesis of virion components - entry (fusion or endocytosis) into host cell - uncoating and nucleic acid release

Release of nucleocapsid into host cytoplasm

______ transduction is the result of excision errors made as temperate phages transition from a lysogenic to a lytic cycle

Specialized

Although live animals and fertilized chicken eggs have been used to cultivate animals viruses in the past, these have now been largely replaced by ____ culture

cell

The process by which the viral nucleic act is released from the protective protein coat is ____ - shedding - uncoating - absorption - release

uncoating

The advantageous genes that can be transferred by transduction are genes for: - sugar fermentation - toxin production - drug resistance - all of the answer choices are correct - none of the answer choices are correct

all of the answer choices are correct

Some viruses trigger ____ as a means of being released - apoptosis - hemolysis - plasmolysis - lysis

apoptosis

Every virus particle contains - ribosomes - DNA and RNA - either DNA or RNA - DNA - phospholipids

either DNA or RNA

Which form of transduction results from packaging errors during phage assembly? - immortalized - compartmentalized - generalized - marginalized

Generalized

Because of their ability to multiple indefinitely in vitro, established cell lines are made up of _____ cells. - tumor - monkey - mouse -normal - bacterial

Tumor

removal of the capsid to release the virus nucleic acid into the host cytoplasm is called ____ - uncoating - endocytosis - decoating - desynthesis - fusion

Uncoating

After entry of the bacteriophage into the host cell, a phage enzyme - breaks the viral capsid into fragments - breaks down the host cell nuclear membrane - breaks down the host cell cytoplasmic membrane - activates host cell ribosomes - breaks the host DNA into fragments

breaks the host DNA into fragments

In a lysogenized bacterium, ____ of the prophage results in a lytic infection - replication - excision - integration - repression

excision

In acute viral infections, although the infected house cells may die, the host may survive because ____ - the virus can only infect a few specific cell types that are quickly destroyed - the virus stops replicating because it exhausts all available nutrients - the host always takes medication that destroys the virus - the host's immune system may gradually eliminate the virus

The hosts immune system may gradually eliminate the virus

Almost immediately upon entry, the viral nucleic acid alters the gene expression of the host cell - true - false

True

In order for viruses to enter host cells, they must bind to receptors on the host cytoplasmic membrane - true - false

True

Specialized Transduction _______ - produces defective phage particles - results from errors in phage head packing - results from errors in excision of the prophage - transfers phage DNA and adjacent host genes - transfers only phage DNA

- produces defective phage particles - results from errors in excision of the prophage - transfers phage DNA and adjacent host genes

Enveloped viruses can derive their envelopes from _____ - the environment - the host cytoplasmic membrane - the host matrix protein - certain host organelles

- the host cytoplasmic membrane - certain host organelles

During the ____ or maturation step in viral multiplication, capsids and genetic material are packaged into visions.

Assembly

Which type of viral infection is characterized by the continuous, low-level production of new virus particles by animals host cells? - acute - chronic - lytic - endemic - filamentous

Chronic

All of the following are required for synthesis of new virus particles in a host cell except _____ - RNA synthesis - genome replication - protein synthesis - homologous recombination

Homologous recombination

Which cytoplasmic effect is a distinct region representing the site of viral replication? - tumor - syncytium - inclusion body - giant cell

Inclusion Body

After host cell DNA is broken down by a viral enzyme - the host cytoplasmic membrane is degraded by viral enzymes - viral proteins begin their assembly and maturation - viral spike proteins are inserted into the bacterial cytoplasmic membrane - the host fragments are reassembled into viral DNA - phage DNA is replicated and phage coat proteins are produced

Phage DNA is replicated and phage coat proteins are produced

A difference between plasmids and fragments of DNA that have been transferred between cells is - only plasmids can transfer drug resistance genes - plasmids can replicate independently - only DNA fragments can transfer drug resistance genes - DNA fragments can replicate independently - DNA fragments are more stable

Plasmids can replicate independently

The enzyme of RNA viruses that lacks proofreading ability and thus makes many mistakes compared to the polymerases of DNA viruses is _____ - transductase - replicase - DNA dependent RNA polymerase - DNA polymerase

Replicase

An enzyme that uses and RNA molecule as a template to make a complementary copy of DNA is called _____ - reverse transcriptase - retro transcriptase - reverse translation - reversible genetics

Reverse Transcriptase

Reassortment of gene segments that encode viral surface proteins that are recognized by the immune system can result in a loss of the immune system's ability to recognize and respond to the virus. This phenomena is called antigenic _____

Shift

A giant multinucleate cell formed as a mechanism of viral spread is called a(n) ______ - syncytium - tumor - oncovirus - inclusion body

Syncytium

In viral entry by endocytosis - the host cell's cytoplasmic membrane surrounds the whole virion and forms a vesicle - lipases degrade the viral coat to release the viral nucleic acid - the host's cell cytoplasmic membrane surrounds only the viral protein coat - the host's cell cytoplasmic membrane surrounds only the viral nucleic acid - viral spikes fuse with the host cell's cytoplasmic membrane to form a vesicle

The host cell's cytoplasmic membrane surrounds the whole virion and forms a vesicle

The negative (-) sense standoff RNA - plays no role - is identical to the (+) sense strand - acts as mRNA to make viral proteins - makes RNA replicase - is used to synthesize more (+) strands

Is used to synthesize more (+) strands

What are the two entry mechanisms used by enveloped viruses? - fusion and exocytosis - fusion and budding - fusion and uncoating - endocytosis and uncoating - fusion and endocytosis

Fusion and Endocytosis

Bacteriophages involved in generalized transduction are ____ phages - temperate - lysogenic - filamentous - lytic - rupturing

Lytic