Bio - Ch 13 Viruses, Viroids and Prions
Outside of living cells, viruses are _______. gaining ATP from the mitochondria using flagella to move to the next host scavenging glucose metabolically inert replicating by binary fission
metabolically inert
In terms of susceptibility to soaps, detergents, and disinfectants, enveloped viruses are ______ non-enveloped viruses. less susceptible than more susceptible than as susceptible as
more susceptible than
Naked viruses do not have an outer lipid bilayer. These viruses are called _____-_____ viruses
non-enveloped
Of the single-stranded RNA viruses, some types have a ______ genome, which also serves as mRNA. (+) strand (-) strand
(+) strand
An infectious agent that consists of protein and no nucleic acid is called a(n) _____
prions
Mad cow disease and chronic wasting disease are caused by infectious agents called _____
prions
RNA viruses have a higher mutation rate than DNA viruses because replicases typically lack _____ ability
proofreading
The stage of viral multiplication at which budding occurs is ______. release absorption synthesis assembly penetration
release
In _____ transduction, only bacterial genes adjacent to the prophage can be transferred.
specialized
_____ transduction is the result of excision errors made as temperate phages transition from a lysogenic to a lytic cycle.
specialized
A ______ phage can either cause a lytic infection or can incorporate its DNA into the host genome as a prophage. latent lysogenic lytic temperate prophage
temperate
Enveloped viruses can derive their envelopes from ______. the host matrix protein the environment the host cytoplasmic membrane certain host organelles
the host cytoplasmic membrane certain host organelles
A viral RNA genome that cannot be immediately translated into protein is a ______. neutral-sense (+) strand non-sense (-) strand
(-) strand
Replication of temperate phages and lytic phages have which steps in common? Genome entry Attachment Integration of the viral genome into the host genome Release Assembly Biosynthesis of viral components
Genome entry Attachment Release Assembly Biosynthesis of viral components
Which are the two main criteria used in classifying viruses? Capsid diameter Genome structure Geographic distribution Host range Pathogenic potential
Genome structure Host range
In which type of infection does the virus remain in the host for years, sometimes without symptoms? Primary Acute Secondary Persistent
Persistent
_______ virus-associated cancers are preventable. No All Most Some
Some
Human cells are larger than viruses by which size factor? Thousand Billion Million Trillion
Thousand
What mechanisms do newly assembled viruses use to leave their host cell? Triggering apoptosis Triggering endocytosis Budding Fusion
Triggering apoptosis Budding
True or false: Bacteriophages are important medically because they can be used to prevent the growth of food-contaminating pathogens.
True Reason: Bacteriophage preparations have been approved for use to prevent the growth of pathogens such as Listeria monocytogenes, Salmonella enterica, and E. coli H157:O7 on food.
True or false: Viral particles can be shed from a host in feces, urine, genital secretions, blood, or mucus and saliva released from the respiratory tract during coughing or sneezing, allowing for transmission to a new host.
True Reason: Viral particles are shed from the host in bodily secretions.
Tumors are abnormal growths that result from a malfunction in the regulation of ______. cellular respiration immune response cell growth
cell growth
This image shows a(n) ______ virus. icosahedral helical complex enveloped
complex
Which suffix represents a viral genus? -virus -viron -viridae No specific suffix
-virus
Which of the following describes the various viral parts coming together to produce virions? Absorption Release Penetration Assembly
Assembly
Which of the following are classified as persistent infections? Chronic infections Latent infections Contagious infections Acute infections Endemic infections
Chronic infections Latent infections
Which of the following are diseases caused by prions? Acquired immune deficiency syndrome Creutzfeldt-Jakob disease Bovine spongiform encephalopathy Multiple sclerosis Scrapie
Creutzfeldt-Jakob disease Scrapie Bovine spongiform encephalopathy
The nucleocapsid is composed of ______. nucleic acid in the ribosome protein located in the nucleus DNA and RNA and protein DNA or RNA, and protein
DNA or RNA, and protein
Which types of viruses are released by budding? DNA viruses Enveloped viruses Non-enveloped viruses RNA viruses
Enveloped viruses
True or false: There is no need to classify viruses because they are not living organisms.
False Reason: Although viruses are not living, classification is still important for identification and study.
Identify all the methods by which an enveloped virus can gain entry into animal cells. Fusion of the viral envelope and the cell membrane Endocytosis of the virus by the host cell Injection of viral nucleic acids across the cell membrane
Fusion of the viral envelope and the cell membrane Endocytosis of the virus by the host cell
Which form of transduction results from packaging errors during phage assembly? Marginalized Compartmentalized Specialized Generalized Immortalized
Generalized
What are the two types of transduction? Specialized Secondary Specific Primary Generalized Adaptive
Generalized Specialized
Which of the following are the three general shapes of most viruses? Helical Diamond Icosahedral Spherical Complex
Icosahedral Helical Complex
Which of the following statements about prions are true? Infectious prion proteins may convert normal prion proteins into an abnormal form. Infectious prion proteins are insoluble and aggregate in brain tissue. Normal prion proteins are resistant to destruction by proteases. Infectious prion proteins have a different shape from normal prion proteins. Both normal and infectious prion proteins are easily destroyed by heat and chemicals.
Infectious prion proteins may convert normal prion proteins into an abnormal form. Infectious prion proteins are insoluble and aggregate in brain tissue. Infectious prion proteins have a different shape from normal prion proteins.
How does bacteriophage nucleic acid enter the host cell? Injection Phagocytosis Engulfment Pinocytosis
Injection
Why are bacteriophages easier to study than animal viruses? It is easier to grow the bacteriophage host cells in the lab. Bacteriophages are larger than animal viruses. Animal viruses are obligate intracellular parasites while bacteriophages are not.
It is easier to grow the bacteriophage host cells in the lab.
______ assays are routinely used to quantify phage particles in environmental samples such as sewage. Prion Plaque Phage Colony
Plaque
Which of the following statements describes the mechanism by which prions replicate? PrP^C interacts with RNA, converting it to PrP^SC. Prion replication depends on DNA polymerase. PrP^SC interacts with PrP^C, converting it to PrP^SC. PrP^C interacts with PrP^SC, converting it to PrP^C.
PrP^SC interacts with PrP^C, converting it to PrP^SC.
During the proposed mechanism of prion replication, the infectious prion protein ______ interacts with the normal protein ______, causing it to misfold. PrP^SC; PrP^C PrP^C; PrP^SC PrP^C; PrP^C PrP^SC; PrP^SC
PrP^SC; PrP^C
Match each gene type with the correct description. Proto-oncogene Tumor suppressor gene - Stimulates cell growth - inhibits cell growth
Proto-oncogene - Stimulates cell growth Tumor suppressor gene - inhibits cell growth
Reverse transcriptase is a(n) ______ polymerase. RNA-dependent RNA DNA-dependent RNA RNA-dependent DNA DNA-dependent DNA
RNA-dependent DNA
Replicases are ______ polymerases. RNA-dependent RNA DNA-dependent RNA RNA-dependent DNA
RNA-dependent RNA
Which of the following processes are required for production of virus particles in a host cell? Replication of host genome Replication of viral genome Transcription of viral genes Cleavage of host polypeptides Translation of viral genes
Replication of viral genome Transcription of viral genes Translation of viral genes
Which form of transduction results from excision errors during the transition from a lysogenic to lytic cycle? Specialized Generalized Immortalized Compartmentalized Marginalized
Specialized
Which of the following are non-cellular infectious agents? Protozoa Fungi Viruses Prions Viroids Bacteria
Viruses Prions Viroids
Which of the following statements about viruses are true? Viruses contain RNA or DNA but not both. Viruses contain both DNA and RNA in one capsid. The viral capsid is composed of protein. The viral capsid is composed of carbohydrates.
Viruses contain RNA or DNA but not both. The viral capsid is composed of protein.
In single-stranded (-) RNA viruses, the enzyme replicase is important because it uses (-) RNA ______. as a template to make (+) DNA which integrates in the host genome as a template to make (+) RNA, which can be used for protein synthesis to make more (-) RNA to be packaged into newly assembled viral particles
as a template to make (+) RNA, which can be used for protein synthesis
During the _____ or maturation step in viral multiplication, capsids and genetic material are packaged into virions.
assembly
Phage components are put together into mature virions during the _____ step of the lytic cycle.
assembly
The T4 phage lytic cycle is divided into five steps. Which one is shown here? synthesis genome entry attachment release assembly
assembly
In order to infect an animal cell, viruses must ______. attach to receptors on the host cytoplasmic membrane inject their DNA through the host cell membrane modify host cell receptors into glycoproteins inject their RNA through the host cell membrane
attach to receptors on the host cytoplasmic membrane
The binding of a bacteriophage surface protein to a host cell receptor is called ______. attachment fixation synthesis assembly entry release
attachment
A generalized infection cycle of an animal viruses can be divided into five steps: 1. _____; 2. _____ entry; 3. _____; 4. assembly; and 5. _____
attachment or adsorption genome synthesis or biosynthesis release or lysis
Viruses that infect bacteria are called
bacteriophages or phages
Infectious agents that have a simpler structure than viruses include ______. viroids only prions only both viroids and prions neither viroids nor prions
both viroids and prions
Enveloped viruses exit host cells by _____ ; non-enveloped viruses are released upon _____ of the host cell.
budding apoptosis or death
A _____ tumor is one that can metastasize, or spread to nearby tissue.
cancerous or malignant
The viral genome is protected from the environment by a protein shell called the ______. capsule capsid cyst envelope
capsid
Oncoviruses are viruses that can ______. enter the cell only via endocytosis cause a lytic or a lysogenic infection enter into a latent state in humans. cause cancer in humans
cause cancer in humans
The hepatitis B virus sometimes causes an infection that results in a continuous and low-level production of virus particles. This type of infection pattern is specifically described as a(n) _____ viral infection.
chronic
When an enveloped virus gains entry to an animal cell by fusion, the virus envelope fuses with the ______. cytoplasmic membrane host vesicle nucleocapsid nuclear membrane
cytoplasmic membrane
Mutations in the influenza virus genome can result in minor changes in key viral surface proteins. This type of variation is called antigenic _____
drift
Viral genomes can be ______. single-stranded only double-stranded only double-stranded DNA or single-stranded RNA either single-stranded or double-stranded
either single-stranded or double-stranded
Animal viruses that do not have an envelope can only enter their host cell by _____
endocytosis
The process by which a virus is taken up by a host cell as a result of the host cell's cytoplasmic membrane surrounding the virion to form a vesicle is called ______. budding exocytosis lysis endocytosis
endocytosis
A non-enveloped virus can gain entry into animal cells via ______. injection of viral nucleic acids across the cell membrane fusion of the viral envelope and the cell membrane endocytosis of the virus by the host cell
endocytosis of the virus by the host cell
The phospholipid bilayer found surrounding the capsid of some viruses is the ______. phagosome matrix envelope cell membrane vacuole
envelope
The virus that causes COVID-19 is _______, and phages are tyoically _______. non-enveloped; enveloped non-enveloped; non-enveloped enveloped; enveloped enveloped; non-enveloped
enveloped; non-enveloped
True or false: DNA viruses can only replicate when the host cell is replicating its own genome.
false
True or false: Lysogens are more susceptible to reinfection by the same type of phage.
false lysogens are immune to superinfection
The replication scheme of double-stranded DNA viruses ______. involves a reverse transcriptase enzyme is very different from replication of single-stranded viruses follows the central dogma of molecular biology
follows the central dogma of molecular biology
Enveloped viruses of animals enter the host cell by one of two mechanisms: 1. _____ with the host membrane; and 2. _____
fusion endocytosis
_____ transduction is the result of packaging errors during the assembly stage of phage replication.
generalized
Bacteriophages play a role in two types of transduction: _____ and _____
generalized specialized
Any gene of the donor cell can be transferred to the recipient cell. This statement describes what type(s) of transduction? specialized transduction only neither generalized nor specialized transduction both generalized and specialized transduction generalized transduction only
generalized transduction only
In this figure, the ______ stage of the T4 phage lytic cycle is shown. assembly genome entry release synthesis attachment
genome entry
Key characteristics used in the classification of viruses are ______. presence or absence of a capsid presence or absence of an envelope protein structures of capsids and spikes genomic structure and host range
genomic structure and host range
In the case of animal viruses, the molecules that viral spikes attach to on the host cell in order to gain entry are typically ______. peptidoglycans lipoproteins glycoproteins lipopolysaccharides
glycoproteins
During the process that leads to a lysogenic infection, which of the following inserts the phage DNA into a bacterial chromosome? gyrase integrase isomerase polymerase lysozyme
integrase
infection of bacteria by ______ phages always ends with the lysis of the host cell
lytic virulent T4
Match each tumor type to the correct statement. malignant benign - spreads to nearby tissue - does not spread to nearby tissue
malignant - spreads to nearby tissue benign - does not spread to nearby tissue
The smallest virus is approximately 10 ______ in diameter. millimeters nanometers centimeters micrometers
nanometers
At a minimum, all viruses are composed of ______. lipids nucleic acids proteins carbohydrates
nucleic acids proteins
In animals, replication of most DNA viruses occurs within the host cell's _____
nucleus
Most animal DNA viruses replicate within the host cell's ______. mitochondria nucleus lysosomes
nucleus
Because they are dependent on host cells, viruses are classified as ______. facultative anaerobes mutualistic extracellular parasites obligate intracellular parasites synergistic
obligate intracellular parasites
Viruses that can cause cancer in humans are known as _____ viruses
oncoviruses
_____ infections remain for years, or even the lifetime of the host, sometimes without any symptoms.
persistent or chronic
A circular zone of clearing of phage-lysed bacteria in a lawn of bacteria is referred to as a(n) ______. prophage biofilm colony plaque capsid
plaque
_____ are the causative agents of transmissible spongiform encephalopathies.
prions
In a lysogenic infection, the phage DNA that is incorporated into the bacterial host genome is called a ______. temperate prophage bacteriophage provirus persistent infection lysogenic
prophage
Control of cell growth and division are controlled by two sets of genes: those that stimulate growth are called _____-_____ , and those that inhibit growth are called _____ _____ genes
proto-oncogenes tumor suppressor
The enzyme of RNA viruses that typically lacks proofreading ability and thus makes many mistakes compared to the polymerases of DNA viruses is ______. DNA polymerase DNA-dependent RNA polymerase transductase replicase
replicase
The virally encoded polymerase needed for replication of RNA viruses is called a _____
replicase
HIV is described as a _____ because it uses reverse transcriptase to make a DNA copy from its RNA genome.
retrovirus
Viruses that have an RNA genome and use reverse transcriptase to synthesize a DNA copy of that genome are called ______. viroids retroviruses reverse viruses autoviruses
retroviruses
An enzyme that uses an RNA molecule as a template to make a complementary copy of DNA is called ______. reverse translation reversable genetics retro transcriptase reverse transcriptase
reverse transcriptase
Reassortment of gene segments that encode viral surface proteins recognized by the immune system can result in a loss of the immune system's ability to recognize and respond to the virus. This phenomenon is called antigenic _____
shift
Attachment of animal viruses to the host cell typically occurs by means of ______. a membrane tail fibers a capsid spikes the envelope
spikes
Many animal viruses have proteins called _____ that attach to receptors on host cells.
spikes
Bacteriophages that can enter into a lytic cycle or a lysogenic cycle are called _____ phages
temperate
In acute viral infections, although the infected host 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's immune system may gradually eliminate the virus the host always takes medication that destroys the virus
the host's immune system may gradually eliminate the virus
A capsid is ______. the viral genome that integrates into the host chromosome the protein coat that surrounds the viral genome the lipid bilayer that forms on the outside of some viruses
the protein coat that surrounds the viral genome
In single strand (+) RNA viruses, ______. the viral RNA functions as a ribozyme for protein synthesis the viral genome functions as mRNA and is translated a (-) RNA replicase is synthesized from the (+) RNA template
the viral genome functions as mRNA and is translated
Viruses are challenging to study because ______. they are obligate intracellular parasites they are composed of nucleic acid and protein they can only be seen using an electron microscope they can only be seen using a light microscope
they are obligate intracellular parasites they can only be seen using an electron microscope
Bacteriophages that exit the host cell at the end of an infection by lysing it are called _______ phages. filamentous lysogenic virulent pathogenic
virulent
Some viruses carry a DNA sequence called an _____ that promotes uncontrolled growth and can result in tumors in host organisms.
oncogene
Transmissible spongiform encephalopathies are caused by ______. bacteria satellite viruses viroids fungi prions
prions
Specialized transduction ______. results from errors in phage head packing results from errors in excision of the prophage transfers only phage DNA transfers phage DNA and adjacent host genes produces defective phage particles
results from errors in excision of the prophage transfers phage DNA and adjacent host genes produces defective phage particles
This figure highlights a stage of the T4 phage lytic cycle known as _______. genome entry synthesis release attachment
synthesis
Phage DNA and proteins are made during the _____ step of the T4 lytic cycle.
synthesis biosynthesis
Which type of infection can be characterized by the sudden onset of symptoms of a relatively short duration? Acute Primary Secondary Persistent
Acute
Which of the following statements about virus nucleic acid is true? All viruses contain protein and DNA. All viruses contain protein and RNA. Viruses contain either DNA or RNA. Viruses contain both DNA and RNA.
Viruses contain either DNA or RNA.
There are two possible outcomes for phage replication strategies. In a(n) _____ infection, new particles are synthesized.
productive
The term _____ is used to describe the rupture or bursting of a bacterial cell following a phage infection.
release lysis cytolysis
The replication strategy of viruses can be divided into three general categories: those used by ______. enveloped viruses reverse transcribing viruses DNA viruses RNA viruses
reverse transcribing viruses DNA viruses RNA viruses
Consequences of lysogeny include ______. lysogenic conversion phage induction and conversion morphological changes immunity to superinfection
lysogenic conversion immunity to superinfection
Some viruses carry a(n) ______ that can promote uncontrolled growth, leading to tumor formation in host organisms. interferon recombinant oncogene plasmid
oncogene
DNA viruses often encode their own DNA _____ for DNA synthesis, which allows them to replicate even if the host cell is not actively duplicating its own chromosome.
polymerase
Which facts best support the position that viruses are not living organisms? Viruses are very small. Viruses are agents of disease. Viruses are inert outside of a host. Viruses are not prokaryotic. Viruses cannot reproduce on their own.
Viruses are inert outside of a host. Viruses cannot reproduce on their own.
The accumulation of mutations in genes that encode viral surface proteins recognized by the immune system results in a type of antigenic variation called ______. antigenic drift antigenic slip antigenic shift antigenic evasion
antigenic drift
When two different strains of a segmented virus enter the same cell, reassortment of the gene segments can occur, resulting in ______. antigenic drift evasion slip antigenic shift
antigenic shift
In enveloped viruses, sandwiched between the nucleocapsid and the envelope is the ______. matrix protein endocapsid exocapsid nucleocapsid exoskeleton
matrix protein
Viral infections that result in the formation of new virus particles are described as ______. primary horizontal latent lateral productive
productive
Match each possible outcome of phage replication with the correct definition. productive infection latent state - viral genome reamins silent within the cell - new viral particles are produced
productive infection - new viral particles are produced latent state - viral genome remains silent within the cell
The range of cell types, tissues and species that a virus can infect is referred to as its host ______. range profile spectrum identity
range
The viral proteins that stick out from either the lipid bilayer of enveloped viruses or the capsid of non-enveloped viruses, and attach to host cells, are ______. capsids spikes matrix proteins nucleocapsids capsomers
spikes
The replication strategies of animal viruses can be divided into three general categories: those used by _____ viruses, _____ viruses, and reverse transcribing viruses
DNA RNA
One of the symptoms of a respiratory virus infection is coughing and sneezing. This allows ______. viral particles to be shed from the host and transmitted to a new host even more viral particles from the environment to access the host respiratory tract
viral particles to be shed from the host and transmitted to a new host
Match the genome of each type of RNA virus with its description of function. (+) strand genome (-) strand genome Double-stranded genome - consists of both a (+) and (-) strand - serves as mRNA - is the complement to mRNA
(+) strand genome - serves as mRNA (-) strand genome - is the complement to mRNA Double-stranded genome - consists of both a (+) and (-) strand
A bacteriophage plaque assay is designed to enumerate phage particles. Place these steps in the correct order, starting with the host cell prep at the top. - Host bacteria and dilution of viral sample are mixed in liquid soft-agar. - Dilutions of viral samples is prepared. - Mixture is poured on top of plate and allowed to harden. - Circular zones of clearing in bacterial growth are observed and counted. - Regular bacterial growth plates are prepared. - Plates are incubated overnight.
1. Regular bacterial growth plates are prepared. 2. Dilutions of viral samples is prepared. 3. Host bacteria and dilution of viral sample are mixed in liquid soft-agar. 4. Mixture is poured on top of plate and allowed to harden. 5. Plates are incubated overnight. 6. Circular zones of clearing in bacterial growth are observed and counted.
List the steps of an animal virus infection cycle in the correct order. Start with the earliest at the top. assembly release attachment penetration and uncoating synthesis of viral proteins and replication of the genome
1. attachment 2. penetration and uncoating 3. synthesis of viral proteins and replication of the genome 4. assembly 5. release
Which of the following infections are analogous to lysogenic infections by bacteriophages in that they involve a viral genome that is silent in the host cell? Persistent Acute Latent Chronic
Latent
Which of the following describe a type of relationship that bacteriophages can have with their host? Latent infection where host cell genotype is changed Latent infection where the host cell lyses Productive lytic infection
Latent infection where host cell genotype is changed Productive lytic infection
Replication of single-stranded DNA viruses is quite similar to that of double-stranded DNA viruses, except that ______. the single-stranded DNA molecule must be reverse transcribed into cDNA a copy of RNA must be synthesized to serve as the template for the synthesis of double-stranded DNA a complement to the single-stranded DNA molecule must be synthesized the single-stranded DNA forms hairpin loops, making a complementary strand unnecessary
a complement to the single-stranded DNA molecule must be synthesized
A prion is best described as ______. an RNA infectious agent an obligate anaerobe a proteinaceous infectious agent an obligate intracellular parasite
a proteinaceous infectious agent
Infections that have a sudden onset of symptoms of relatively short duration are described as _____ infections.
acute
Which type of infection can be characterized by the sudden onset of symptoms of a relatively short duration? Acute Secondary Primary Persistent
acute
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
Which are the two major categories of viral infections? acute latent persistent chronic Asymptomatic
acute persistent
Following generalized transduction, DNA from the donor cell may be integrated into the recipient cell chromosome by _____ recombination
homologous
All of the following are required for synthesis of new virus particles in a host cell EXCEPT ______. protein synthesis genome replication RNA synthesis homologous recombination
homologous recombination
Symptoms of acute viral diseases result from ______. host tissue damage host immune response lysogenic conversion viral budding
host tissue damage host immune response
At least 15 ______ are associated with the development of cancers. A vaccine that protects against the serotypes most highly associated with cervical cancers and some other cancers is available. herpes simplex viruses rhinoviruses human papillomaviruses human immunodeficiency viruses
human papillomaviruses
Most viruses have one of three different shapes: _____, _____, and _____
icosahedral helical complex
The process of a prophage being excised and entering the lytic cycle is ______. lysis lysogeny adsorption induction
induction
Through the process of phage _____ , a prophage is excised and enters the lytic cycle.
induction
Viruses are best described as _______. obligate extracellular microorganisms infectious proteins infectious agents obligate anaerobes
infectious agents
The study of bacteriophages has advanced much faster than investigations on animal viruses in part because ______. it is easier to grow bacterial cells than animal cells there are only a few different bacteriophages bacteriophages are much larger than animal viruses it is easier to grow animal cells than bacterial cells
it is easier to grow bacterial cells than animal cells
A viral infection in which the viral genome is integrated into an animal host cell chromosome, yet can reactivate to cause a productive infection, is categorized as a(n) _____ infection
latent
The two categories of persistent infections are _____ and _____
latent chronic
Enveloped viruses have an outer layer made up of _______. carbohydrate lipid protein nucleic acid
lipid
Retroviruses may lead to latent infections because ______. their genome is a mix of RNA and DNA, both of which a host cell also contains their RNA can suppress all normal host cell activities they can integrate a DNA copy of their genome into the host chromosome they can integrate their RNA genome into the host chromosome
they can integrate a DNA copy of their genome into the host chromosome
Bacteriophages play a fundamental role in a type of horizontal gene transfer called _____
transduction
What term is used to describe the transfer of genetic information from one bacterium to another bacterium by a bacteriophage? conjugation transduction translocation transformation
transduction
True or false: Normal prion proteins can have the same amino acid sequence as the abnormal form of the protein.
true the proteins differ in their folding and shape
An abnormal growth of tissue resulting from a malfunction in the normally highly regulated process of cell growth is a _____
tumor
After a virus enters a cell, the nucleic acid separates from the protein coat, a process called _____
uncoating
The process by which the viral nucleic acid is released from the protective protein coat is ______. absorption uncoating release shedding
uncoating
Which of the following about classifying viruses is FALSE? An online database classifying viruses is kept by the ICTV (International Committee on Taxonomy of Viruses). It is not as important as classifying organisms since they are not living entities. Viruses can be classified based on different viral characteristics. It provides a useful way to identify and study viruses.
It is not as important as classifying organisms since they are not living entities.
Which is most important for attachment of a virus to a host cell? Viral shape and size Number of genes carried by the virus Viral specificity for host receptors
Viral specificity for host receptors
Regarding animal viruses, which of the following statements are true? 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 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. Blocking a host receptor with a drug would prevent a virus from infecting that cell.
True or false: All virus infections can be clearly categorized as either acute or persistent.
false some viruses cause both type of infection at various stages, e.g. HIV
HIV infection ______. is a persistent infection that continues with or without symptoms for years, or even the life span of the host has features of both acute and persistent infections is an acute infection with sudden onset of symptoms that are then cleared
has features of both acute and persistent infections
In the case of retroviruses, reverse transcriptase uses a viral RNA template to synthesize DNA, which can then be ______. integrated into a host cell chromosome where it remains latent transported to the cytoplasmic membrane for export to neighboring cells translated directly to form multiple new viruses transcribed and translated to form new virions
integrated into a host cell chromosome where it remains latent transcribed and translated to form new virions
Lysogeny is best described as ______. replication of virions inside of a host cell integration of the viral genome into the host chromosome fragmentation of the host chromosome by nucleases lysis of the host cell by lysozyme
integration of the viral genome into the host chromosome
Before enveloped viruses bud from a host cell, specific viral proteins insert into the host membrane. These proteins become ______. matrix proteins virus capsomeres viral envelope viral spikes
viral spikes
True or false: Enveloped and non-enveloped viruses all mature fully in the cytoplasm of the host cell.
False Reason: Non-enveloped viruses mature in the cytoplasm but enveloped viruses acquire their envelope as they exit the host cell.
The suffix ______ indicates a viral family. -viridae -viron -virus -virinae
viridae
Which statements regarding viruses are true? The terms virus and phage are interchangeable. Some viruses can infect both prokaryotic cells and eukaryotic cells. Viruses that infect bacteria are called bacteriophages.
Viruses that infect bacteria are called bacteriophages.
The study of viruses is important because ______. bacteriophages play a significant ecological role in reducing bacterial populations in nature there are many medically important viruses that cause disease bacteriophages can be a vehicle for horizontal gene transfer in bacteria viruses cause all known human diseases bacteriophages play a role in bacterial conjugation
bacteriophages play a significant ecological role in reducing bacterial populations in nature there are many medically important viruses that cause disease bacteriophages can be a vehicle for horizontal gene transfer in bacteria
In the case of RNA viruses that have a single strand (+) RNA genome, the viral genome ______. is reverse transcribed into RNA serves as a template for the synthesis of more (+) strand RNA can be translated to make proteins is used as a template to make complementary (-) RNA strands that act as templates to produce more (+) RNA strands
can be translated to make proteins is used as a template to make complementary (-) RNA strands that act as templates to produce more (+) RNA strands
