TEST BANK for Fundamentals of Molecular Virology 2nd Edition by Acheson

TEST BANK for Fundamentals of Molecular Virology 2nd Edition by Acheson. Package Title: Testbank Course Title: Acheson 2nd edition Chapter Number: 01 Question type: Multiple Choice 1) Which of the following terms describes the protein shell that surrounds the viral genome? a) capsid b) envelope c) matrix d) virion e) capsomere Answer: a 2) Which of the following would not be a nucleic acid form found in a viral genome? a) dsDNA b) ssDNA c) dsRNA d) ssRNA e) an RNA:DNA hybrid Answer: e 3) Which of the following is an enzyme that most RNA viruses encode in their genome? a) DNA-dependent-RNA-polymerase b) RNA-dependent-RNA-polymerase c) DNA-dependent-DNA-polymerase d) DNA-dependent-RNA-polymerase e) RNA-dependent-protein-synthetase Answer: b 2 4) Viruses play a major role in the ecology of the ocean by doing which of the following? a) By infecting photosynthetic bacteria and increasing their growth. b) By infecting harmful bacteria found in the ocean and limiting their growth. c) By killing off fish and preventing them from becoming too plentiful. d) By lysing unicellular organisms and releasing carbon and oxygen back into the ocean. e) All of the above statements are correct. Answer: d 5) If you wanted to show that an infectious agent is a virus, what experiment could you do? a) Show that the agent can be seen under a light microscope. b) Show that agent contains a lipid membrane. c) Show that the agent can form single colonies on an agar plate. d) Show that the agent can be diluted and can still cause disease in an animal. e) Show that the agent can pass through a porcelain filter and is still infectious. Answer: e 6) What does the word “virus” mean in Latin? a) infectious agent b) liquid c) poison d) death e) disease Answer: c 7) The word “phage” is a shortened version of the name of a virus that can infect which type of organism? a) bacterial cell b) human cell c) eukaryotic cell d) plant cell e) inset cell Answer: a 3 8) The study of which group of viruses led to the discovery of cellular genes that can promoter cancer in animal cells? a) papillomaviruses b) retroviruses c) adneoviruses d) polyomaviruses e) picornaviruses Answer: b 9) When doing a plaque assay with human or animal cells, a layer of nutrient media mixed with agar is put on top of the cells after they have been infected with the diluted virus. What is the major purpose of this agar layer? a) It helps to feed the cells as they grow. b) It promotes the replication of the virus. c) It makes the infected cells easier to visualize. d) It limits the movement of virus particles. e) All of the above are correct. Answer: d 10) To start an experiment, you do an infection by putting 0.5 ml of a virus stock that has a titer of 6 x 107 pfu/ml onto a plate of animal cells that contains 5 x 106 cells. What is the multiplicity of infection for this experiment? a) 12 b) 6 c) 5 d) 3 e) 1 Answer: b 11) During a single growth cycle experiment, the titer of extracellular and intracellular virus drops in the first hour. What explains this observation? a) The virus is inactivated by antibodies in the medium. b) The virus is inactivated by cellular enzymes. 4 c) The virus enters the cell and is uncoated. d) The virus binds to the cells in the dish and can’t be released. e) The cell’s antiviral defenses prevent replication of the virus Answer: c 12) What is another term for an RNA-dependent-DNA-polymerase? a) DNA polymerase b) RNA polymerase II c) RNA replicase d) RNA transcriptase e) Reverse transcriptase Answer: e 13) Plant viruses use which cellular structures to spread between host cells? a) endosomes b) plasmodesmata c) plasma membranes d) vesicles e) receptors Answer: b 14) All viruses that use a negative-sense RNA genome must package which of the following proteins in their virion? a) RNA-dependent-RNA-polymerase b) matrix protein c) RNA helicase d) RNA methylase e) scaffolding protein Answer: a 15) Which of the following is a description of a plaque? a) A viral particle as seen by electron microscopy. b) A region of dead cells in a monolayer of infected cells. 5 c) A skin lesion caused by a virus infection in an animal. d) A button of red blood cells seen in a hemagglutination assay. e) A region of crystallized virus particles in an infected cell. Answer: b 16) Which of the following processes in cells was NOT discovered by studying a virus? a) the sequence of the genetic code. b) DNA replication in both prokaryotic and eukaryotic cells c) DNA is the genetic material d) regulation of gene expression in eukaryotic cells. e) mRNA splicing in eukaryotic cells Answer: a 17) You are given a solution of virus and asked to determine the titer. You carry out a plaque assay with 0.5mls of a 105 dilution of the virus solution and obtain an average of 150 plaques. What is the titer of the solution? a) 1.5 x 105 pfu/ml b) 3 x 105 pfu/ml c) 1.5 x 107 pfu/ml d) 3 x 107 pfu/ml e) 1.5 x 108 pfu/ml Answer: d 18) The Baltimore classification system describes the relationship between a viral genome and the: a) the complementary genome sequence. b) early viral proteins. c) early mRNAs. d) cellular polymerases. e) Latin classification system. Answer: c 19) If the genome of a positive-strand RNA virus, which has been purified away from all of the virion proteins, was injected into the cytoplasm of an appropriate host cell, what would happen first? a) The genome would be copied into complementary negative RNA. 6 b) The genome would be translated by cellular ribosome’s. c) The genome would be transcribed by a cellular RNA-dependent-RNA-polymerase. d) The genome would be transcribed by a viral RNA-dependent-RNA-polymerase. e) None of the above. Answer: b 20) If the genome of a negative-strand RNA virus, which has been purified away from all of the virion proteins, was injected into the cytoplasm of an appropriate host cell, what would happen first? a) The genome would be copied into complementary negative RNA. b) The genome would be translated by cellular ribosome’s. c) The genome would be transcribed by a cellular RNA-dependent-RNA-polymerase. d) The genome would be transcribed by a viral RNA-dependent-RNA-polymerase. e) None of the above. Answer: e 21) Most DNA viruses that replicate in the nucleus of the host cell use which of the following to transcribe their genes into mRNA? a) cellular DNA-dependent-RNA polymerase b) viral DNA-dependent-RNA polymerase c) viral DNA-dependent-DNA polymerase d) cellular DNA-dependent-DNA polymerase e) viral RNA-dependent-DNA polymerase Answer: a 22) The development of which of the following instruments or techniques in the 1930’s allowed scientists to visualize viral particles for the first time? a) polymerase chain reaction b) electron microscope c) confocal microscope d) thermal cycler e) plaque assay Answer: b Question Type: True/False 7 24) The common cold can be caused by viruses from three different families, some of which have RNA genomes and some of which have DNA genomes. Answer: True 25) The major advantage of a hemagglutination assay to measure the amount of virus particles in a solution is that it is very accurate. Answer: False 26) Phages, viruses that can infect bacterial cells, may someday be used to treat bacterial infections. Answer: True Question type: Essay 27) The particle to plaque ratio for most animal viruses is much greater than one. What are the reasons why not 100% of animal virus particles, as seen under the electron microscope, can productively infect cells? Answer: Not all virus particles as seen under the electron microscope are intact virions capable of binding and entering a host cell. Some virus particles contain defective genomes that lack one or more critical genes necessary for viral replication. Some viral particles contain empty capsids, which means that there is not genome inside the virion. Finally, cells have many antiviral defense mechanisms that can shut down a virus infection before it can be completed. 28) Viruses are not the only obligatory intracellular parasites. Describe how the replication of viruses is different than cellular organisms that replicate inside of cells, like chlamydiae and rickettsiae. Answer: Unicellular parasitic cells that need to replicate inside of other cells do not replicate in the same way that viruses do. First of all, unicellular parasites have their own ribosomes to translate their mRNAs and do not use the host cell ribosomes, like viruses do. In addition they are intact cells that contain their genome entirely within their own cellular membranes and do not release their genome into the host cell, the way that viruses do. These cellular parasites undergo binary fission in the same way that independently living cells do. Viruses do not have their own ribosomes and actually disintegrate their virion, releasing the genome out of the capsid and into the cytoplasm before they begin their replication. They do not undergo binary fission. Package Title: Testbank Course Title: Acheson 2nd edition Chapter Number: 02 Question type: Multiple Choice 1) The lipid membrane that surrounds the nucleocapsid of some virus particles is called the: a) matrix b) tegument c) capsid d) envelope e) glycoprotein Answer: d 2) The nucleocapsid describes the structure that includes the: a) capsid and the genome b) capsid and the envelope c) envelope and the glycoproteins d) helical capsid and an envelope e) icosahedral capsid and an envelope Answer: a 3) Depending on the type of virus, which of the following is a function of the virus capsid? a) To attach to the correct type of host cell. b) To protect the viral genome from nucleases. c) To ensure delivery of the genome into the host cell. d) To protect the viral genome from damage by UV light. e) All of the above functions are correct. Answer: e 4) Virus particles can be visualized with which of the following? a) negative staining of virions with electron microscopy b) negative staining of virions with x-ray diffraction c) negative staining of thin sections of infected cells with electron microscopy d) positive staining in cryoelectron microscopy 9 e) positive staining of infected cells with x-ray diffraction Answer: a 5) Most viruses that use a spherical shaped capsid arrange their capsid proteins with which of the following symmetries? a) cubic b) tetrahedral c) icosahedral d) dodecagon e) helical Answer: c 6) Which of the following is NOT a characteristic of a regular icosahedron? a) It has 12 vertices of 5-fold symmetry. b) It has 20 triangular faces. c) It has 20 sides with 3-fold symmetry. d) It has 30 edges with 2-fold symmetry e) It has 6 square faces. Answer: e 7) How many copies of the capsid protein would there be in an icosahedral capsid with a Triangulation number of 7? a) 70 b) 210 c) 280 d) 420 e) 490 Answer: d 8) Which of the following h and k values will produce a triangulation number of 13? a) 1 and 1 b) 1 and 2 c) 1 and 3 d) 2 and 3 Answer: c 9) The capsid of SV40 contains 360 protein copies. Why is this unusual? a) There is only 1 kind of protein in this capsid. b) 360 is not the correct number of protein capsids for a T = 6 capsid. c) Six is not a mathematically allowed triangulation number. d) The proteins have equivalent interactions. e) The capsid is not large enough to hold the entire genome. Answer: c 10) The Jelly Roll barrel is: a) a structure found in many viral envelope glycoproteins. b) a structure found in many viral capsid proteins. c) the structure the viral genome takes inside of a helical capsid. d) the structure the viral genome takes inside an icosahedral capsid. e) the structure of many helical capsids as the wrap around the genome. Answer: e 11) Which of the following describes the number of subunits per turn in a helical capsid? a) P (pitch) b) (mu) c) (rho) d) Triangulation number e) symmetry Answer: b 12) A very common structure for bacteriophage particles is which of the following? a) an icosahedral head and an envelope b) a naked icosahedral head c) a naked helical tail d) an icosahedral head with a helical tail 11 e) a cubic head with a helical tail Answer: d 13) A Type I membrane protein has which of the following structures? a) Both the C-terminus and the N-terminus face the inside of the virion. b) It passes through the viral envelope multiple times. c) The N-terminus faces outside the virion and the C-terminus faces inside the virion. d) The N-terminus faces inside the virion and the C-terminus faces outside the virion. e) The protein lacks a transmembrane domain and is secreted from the infected cell. Answer: c 14) What does the term “quasi-equivalent” mean with respect to the proteins in an icosahedral capsid? a) If the identical protein is used, it has both 5-fold and 6-fold interactions with the other proteins in the capsid. b) There are different proteins in the capsid with similiar shapes. c) They all use the “jelly-roll” protein structure. d) There can be more than one type of glycoprotein in the envelope. e) All of the proteins interact in a 5-fold arrangement. Answer: a 15) Which of the following is a description of a scaffolding protein? a) A cellular protein that acts as a chaperone during assembly of a helical capsid. b) A viral protein that is used on the outside of an icosahedral capsid during assembly. c) A viral protein used on the inside of an icosahedral capsid during assembly and then removed. d) A protease that trims the proteins during assembly of an icosahedral capsid. e) A energy dependent motor used to package the genome into larger icosahedral capsids. Answer: c 16) A scaffolding protein is important for assembly of an icosahedral capsid….. a) but does not bind to the viral genome. b) but does not become part of the final virion. c) and helps to cut the genome into unit lengths. 12 d) and binds to the host cell receptor. e) and assists the virion in exiting the host cell. Answer: b 17) A packaging sequence is involved in which of the following assembly processes? a) The assembly of the capsid around the genomic nucleic acid. b) The correct binding of capsid proteins to each other. c) The insertion of the viral glycoproteins in the envelope. d) The acquisition of the envelope by the capsid. e) The packaging of the matrix proteins into the virion. Answer: a 18) In a helical nucleocapsid, which of the following MOST affects the LENGTH of the capsid? a) the (mu) value b) the (rho) value c) the size of the genome and the P (pitch) of the helix d) the size of the capsid protein e) None of the above. Answer: c 19) Enveloped virions assemble and acquire their envelope by which of the following mechanisms? a) The nucleocapsids interact directly with the cytoplasmic tails of the envelope glycoproteins and bud through the cellular membrane. b) The nucleocapsids interact with the matrix protein, which interact with the cytoplasmic tails of the envelope glycoprotein, and the virion buds through the cellular membrane. c) The envelope is assembled de novo around the nucleocapsid by cellular enzymes. d) The virion acquires the envelope after it leaves the host cell from extracellular vesicles. e) Both a and b are used by viruses. Answer: e 20) Viral proteins that assemble between the nucleocapsid and the envelope are called a) matrix proteins b) envelope glycoproteins 13 c) scaffolding proteins d) core proteins e) packaging proteins Question Type: True/False 21) It is possible to get high resolution images of enveloped virus particles using x-ray diffraction. Answer: False 22) Some viruses particles have a rigid capsid surrounding an internal membrane. Answer: True 23) Cryoelectron microscopy uses computer reconstruction of images of multiple virions to produce a high resolution image of a virion or capsid. Answer: True. 24) Viral envelopes often have very different lipid compositions than the cellular membranes that they originate from. Answer: False Question type: Essay 25 ) Describe the concept of “quasi-equivalence” as it applies to icosahedral capsid structure. Answer: Quasi-equivalence describes the situation in icosahedrons with triangulation numbers higher than 1 and that use a single protein to assembly their capsid. In these capsids, the protein must interact in a 5-fold symmetry at the 12 vertices and in a 6-fold symmetry in the hexagonal faces. Therefore its interactions are not always identical but depend on the protein’s location within the capsid. 26) Virions are often described as being energetically “metastable”. What does this mean and why is it important for entry and uncoating of the viral genome into the next host cell? 14 Answer: Virons are described as “metastable” because they are not at their lowest, most stable, energy state. If they were, they would not be able to “pop open” to release the genome in the next host cell. Instead, they are like a “Jack-in-the-box”, primed to spring open and release the genome after some triggering event. The triggering event that causes the virion to open and release the genome is often the interaction with the host cell receptor or some other change, like a drop in pH, that occurs during attachment and entry. Often proteolytic cleavage of a virion protein is involved in setting up the metastable state and “setting the spring” that will eventually allow the virion to pop open. Package Title: Testbank Course Title: Acheson 2nd edition Chapter Number: 03 Question type: Multiple Choice 1) Which of the following types of genomes is most commonly found in viruses that can infect fungi? a) ssDNA b) dsDNA c) ssRNA d) dsRNA e) All of the above are found. Answer: d 2) The name of a virus family in the Latin classification system has which of the following endings? a) -viridae b) -virales c) -virinae d) -virus e) -virusdae Answer: a 3) The family classification scheme for DNA bacteriophages is not very useful for describing the evolutionary relationships between these viruses. What is the best explanation for this? a) DNA bacteriophages can infect more than one host species. b) DNA bacteriophages have a wide variety of virion structures. c) The viral genomes are genetic mosaics due to recombination. d) There are too many bacteriophages to classify into families. e) These viruses do not have an evolutionary relationship to each other. Answer: c 4) Which of the following is a type of nucleic acid NOT found as the genome of a virus that can infect vertebrates? a) ssDNA b) dsDNA c) ssRNA d) dsRNA e) All of the above are found. Answer: e 5) Most viruses that infect plants have the following type of genome? a) ssDNA, positive sense b) ssDNA, negative sense c) ssRNA, positive sense d) ssRNA, negative sense e) None of the above. Answer: c 6) What is a possible explanation for why ssDNA viruses have genomes less that 10kb in size? a) ssDNA is not as physically stable as dsDNA. b) ssDNA is not transcribed by host cells. c) ssDNA can form hairpin structures because of base-pairing. d) Larger pieces of ssDNA can not be replicated. e) Larger pieces of ssDNA can not easily enter the host cell. Answer: a 7) An interesting observation is that many highly pathogenic and deadly human viruses have the following type of genome? a) ssDNA, positive sense b) ssDNA, negative sense c) ssRNA, positive sense d) ssRNA, negative sense e) dsRNA 8) Which of the following virus families have the ability to synthesize reverse transcriptase? a) Retroviruses b) Caulimoviruses c) Hepadnaviruses d) None of the above are correct. e) All of the above are correct. Answer: e 9) What distinguishes a satellite virus from a satellite nucleic acid? a) A satellite virus encodes its own capsid protein while a satellite nucleic acid does not. b) A satellite virus packages its own replication protein while a satellite nucleic acid does not. c) A satellite virus requires a helper virus while a satellite nucleic acid does not. d) Genomes of satellite viruses are smaller than those of satellite nucleic acids. e) Satellite viruses do not encode any proteins while satellite nucleic acids do. Answer: a 10) What is a ribozyme? a) A molecule of RNA that is independently capable of replicating without cellular enzymes. b) A molecule of RNA that codes for an enzyme. c) Another name for a small infectious molecule of RNA d) A virus that uses a small piece of RNA as its genome. e) A molecule of RNA that can carry out an enzymatic process. Answer: e 11) According to the RNA World hypothesis, which of the following subcellular entities may have evolved first? a) Retroviruses b) RNA Viruses c) Viroids d) DNA Viruses e) Bacteriophages 12) According to the RNA World hypothesis, which of the following enzymes may have evolved first? a) DNA-dependent RNA polymerase b) DNA-dependent DNA polymerase c) RNA-dependent RNA polymerase d) RNA-dependent DNA polymerase e) self-replicating RNAs Answer: e 13) Which of the following virus families contains viruses with the longest ssRNA genomes? a) Picornaviruses b) Coronaviruses c) Flaviviruses d) Togaviruses e) Bromoviruses Answer: b 14) What is approximately the largest size of a double-stranded DNA genome of a virus that infect vertebrates? a) 25 kbp. b) 50 kbp c) 100 kbp d) 300 kbp e) 500 kbp Answer: d 15) Almost all of the viruses with positive-strand RNA genomes and enveloped virions infect which group of hosts? a) Bacteria. b) Vertebrates c) Plants d) Fungi e) Algae. 16) Which of the following may be a factor in explaining why viral ssRNA genomes are not usually as long as the dsDNA genomes? a) It is much more difficult to package a large ssRNA genome into a capsid. b) Long ssRNA molecules form too many secondary structures that inhibit replication. c) Long RNA genomes are difficult to translate. d) Long RNA genomes are difficult to transcribe. e) Long pieces of RNA are easily broken by mechanical damage. Answer: e 17) The advantage of using a helical instead of an icosahedral nucleocapsid to package a ssRNA genome is….. a) it is more efficient to envelope a helical nucleocapsid than an icosahedral capsid. b) it is easier to produce a helical nucleocapsid than an icosahedral capsid. c) it better protects the genome from degradation inside the cell. d) it requires a smaller protein to build than an icosahedral capsid. e) it requires fewer copies of the nucleocapsid protein than an icosahedral capsid. Answer: c 18) There are a number of small DNA viruses that are highly dependent on their host cells for transcription and replication enzymes. Which of the following could explain the evolutionary origins of these viruses? a) They originated from fragments of the genomes of larger more independent viruses. b) They originated from intracellular plasmids found in bacteria. c) They originated from the genomes of intracellular organelles, such as mitochondria. d) They originated from fragments of cellular DNA that broke away from the cell genome. e) All of the above could be correct. Answer: d 19) The RNA World hypothesis is supported by the observation that: 19 a) there are viruses that still use RNA as their genomic nucleic acid. b) some viruses can covert RNA to DNA. c) some RNA molecules have enzymatic activity. d) some viruses encode RNA-dependent RNA polymerases. e) All of the above support the RNA World hypothesis. Answer: 20) Which of the following characteristics are NOT one of the most important criterion used to classify viruses into families? a) topology of genome (linear or circular) b) strandedness of genome (double or single stranded) c) type of nucleic acid used in genome (DNA or RNA) d) structure of virion e) species of host infected Answer: e Question Type: True/False 21) There are several types of viruses with enveloped virions that can infect plants. Answer: False 22) Retroviruses are the only virus family known to package two copies of its genome. Answer: True. 23) Viroids do not require a helper virus in order to replicate and cause disease. Answer: True Question type: Essay 24) Why is the type of disease caused not the best criteria to use when classifying a virus? 20 Answer: The disease caused by a specific virus is not usually related to the evolutionary history of that virus. Viruses with very different types of genomes, virion structures, and replication pathways can cause the same type of disease. For example, there are at least 5 different viruses that cause a form of hepatitis in humans and these viruses are in 5 different families. Families, which are based on genome and virion structure, represent evolutionary relationships between viruses. 25) Mimivirus, which infects an amoeba, is the largest known dsDNA virus and has a genome larger than some free living bacteria and archae. Even though it encodes many of its own enzymes and even tRNAs, it still does not produce its own ribosomes. Describe the possible evolutionary origin of such a large and complex viruses. Answer: Mimiviruses, along with poxviruses, are thought to have possibly once been independently replicating cells that lost the ability to make their own ribosomes and took on an intracellular parasitic life style. These viruses are capable of synthesizing and processing their mRNAs using mechanisms very similar to those used by the host cell. Another hypothesis is that they may have been precursors to the eukaryotic cell nucleus by at one point becoming incorporated into a prokaryotic cell. Package Title: Testbank Course Title: Acheson 2nd edition Chapter Number: 04 Question type: Multiple Choice 1) Before the viral genome can be transcribed or replicated in a new host cell it must…. a) be trimmed by cellular nucleases. b) be transported through the receptor mediated endocytosis pathway. c) be processed through the cellular exocytosis pathway. d) enter the host cell nucleus and be bound by cellular histone proteins. e) be uncoated in the appropriate compartment of the correct cell type. Answer: e 2) Unenveloped viruses must get their genome past the hydrophobic cell membrane. Some accomplish this by doing which of the following? a) They cause the plasma membrane to lyse. b) They insert viral proteins into a vesicle membrane. c) They inject their genome into the nucleus via the nuclear pore complex d) They create a pore through the membrane and extrude the genome directly into the cytoplasm e) They create a clatherin coated pit during entry 3) Because of the rigid plant cell wall, the entry of plant viruses is difficult. Which of the following is a description of how plant viruses move between individual cells within in a whole plant? a) They move between cells using plasmodesmata. b) They cause the formation of syncytia. c) They use the receptor mediated endocytosis pathway. d) They rely on insect vectors to transfer virions between the cells in a single host. e) They produce movement proteins that can create holes in the plant cell wall, allowing movement of the virions between cells. Answer: a 4) Which of the following is the best description of a syncytia? a) A cellular structure that viruses us to move within a host cell. b) A fusion of two cells causes by viral envelope glycoproteins. c) A structure between two plant cells that viruses can use for cell to cell movement. d) A vesicle involved in the receptor mediated endocytosis pathway. e) A protein that is involved in the transport of proteins into the nucleus. Answer: b 5) Orthymyxoviruses and paramyxoviruses both bind to which receptor on the surface of which host cells? a) an immunoglobulin family receptor protein b) the CD4 protein c) the carbohydrate sialic acid d) the neuraminidase enzyme e) a multiple membrane spanning transport protein Answer: c 6) Which of the following is an example of a virus that requires two different host cell receptors to complete its entry into the host cell? a) HIV-1 b) Adenovirus c) Polio (picornavirus)