Viruses
1) Which of these comprises the viral genome?
a) single-stranded DNA
b) single-stranded RNA
c) double-stranded DNA
d) double-stranded RNA
e) All of these choices are seen in viruses.
2) What is the viral capsid composed of?
a) protein
b) nucleic acid
c) lipid
d) polysaccharide
e) glycogen
8) Viruses that have icosahedral symmetry have ______faces and 12 vertices resulting in a spherical appearance.
a) 10
b) 20
c) 30
d) 40
e) 50
9) Enveloped viruses are mainly associated with which of the following?
a) plants and bacteria
b) animals
c) bacteria
d) plant and animals
e) plants
10) What is the first step in the viral replication cycle?
a) RNA synthesis
b) genome synthesis
c) entry into the cell
d) attachment to the cell
e) viral RNA translation
12) What is the most common way for enveloped viruses to enter animal cells?
a) The virion fuses itself to the cell membrane.
b) The virion directly injects its nucleic acid.
c) Endocytosis of the virion.
d) Through lysis of the cell.
e) Via a hole in the cell membrane.
14) How do bacteriophages invade the bacteria cell?
a) The bacteriophage fuses itself to the cell membrane.
b) The bacteriophage directly injects its nucleic acid.
c) Endocytosis of the bacteriophage.
d) Through lysis of the cell.
e) Via a hole in the cell membrane.
16) Many enveloped viruses exit their host cell through a process called ______.
a) exocytosis
b) budding
c) cell lysis
d) receptor-mediated endocytosis
e) phagocytosis
18) What is the premise of the progressive hypothesis of viral origin?
a) Viruses evolved from symbionts of cells.
b) Viruses evolved from self-replicating nucleic acid segments.
c) Viruses originated from cells that lost the ability to replicate.
d) Viruses were present when the first primordial cells evolved.
e) Viruses arose from fragmented DNA in a cell.
21) The term for bacteriophage DNA that has integrated into the host cell chromosome and replicates along with the host cell chromosome.
a) a plasmid
b) a transposon
c) a prophage
d) a lysogen
e) a retrophage
1) Most likely, “host specificity” of a virus is determined by
a) the type of nucleic acid it contains.
b) the presence or absence of an envelope.
c) viral enzymes.
d) interactions between viral attachment proteins and host cell receptors.
e) viral nucleic acid replication strategies.
2) The viral attachment protein specifically binds to a host cell receptor. All of the following are examples of known host cell receptors except
a) DNA.
b) proteins.
c) glycoproteins.
d) lipopolysaccharides.
e) sialic acids.
3) The ability of a virus or bacteriophage to specifically attach to a host cell occurs through the interactions of the viral attachment protein with the host cell receptor. This binding determines
a) the rate of viral replication.
b) the host range.
c) the mechanism of viral entry.
d) whether or not the virus will contain an envelope.
e) the rate of viral RNA replication.
6) Antiviral drugs that act at the level of host recognition are designed to
a) prevent endocytotic vesicle formation.
b) prevent virus binding to the host cell receptor.
c) enhance antibody production.
d) inactivate viral nucleic acid polymerases.
e) bind to viral metabolic enzymes.
9) The influenza virus gains entry into a host cell by
a) direct injection of its nucleic acid.
b) receptor-independent endocytosis.
c) lysis of the cell membrane.
d) receptor-mediated endocytosis.
e) pinocytosis.
10) The influenza virus gains entry into a host cell by an endocytotic process. The viral nucleocapsid leaves the endosome and enters the cytoplasm through a membrane fusion mechanism. Fusion of the viral envelope with the endosomal membrane is facilitated by
a) a conformation change in the hemagglutinin to expose a fusion protein.
b) the production of a lipase by the influenza virus.
c) sialic acid residues of the receptor proteins.
d) specific viral protein recognition of pores in the endosome vesicle.
e) the production of proteases by the influenza virus.
21) For most double-stranded DNA eukaryal viruses, DNA replication occurs in the ______and translation occurs in the ______.
a) cytoplasm, cytoplasm
b) cytoplasm, nucleus
c) nucleus, nucleus
d) nucleus, cytoplasm
e) mitochondria, cytoplasm
22) Most RNA viruses utilize
a) an RNA-dependent RNA polymerase.
b) a DNA-dependent RNA polymerase.
c) an RNA-dependent DNA polymerase.
d) a DNA-dependent DNA polymerase.
e) reverse transcriptase.
31) Many antiviral drugs are nucleoside analogs. The nucleoside analogs primarily target these enzymes
a) host cell DNA polymerases.
b) host cell RNA polymerases.
c) host cell nucleases.
d) viral nucleic acid polymerases.
e) viral nucleases.
32) The reason nucleoside analogs are effective against viral nucleic acid polymerases is because
a) viral polymerases have a very high rates of polymerization.
b) viral polymerases have a low rate of polymerization.
c) viral polymerases have a high affinity for incorporation of the analogs.
d) viral polymerase activity is inhibited by the analogs.
e) viral polymerase activity is enhanced by the analogs.
33) AZT is a nucleotide analog used to treat people infected with
a) herpes virus.
b) HIV.
c) papilloma virus.
d) influenza virus.
e) polio virus.
10.A key factor in the evolution of killer strains of influenza is that it
A.only has 8 genes.
B.has an RNA genome.
C.contains reverse transcriptase.
D.has a segmented genome.
E.has a circular chromosome.
7.Which of the following best describes the genome of influenza virus?
A.negative strand segmented RNA
B.positive strand segmented RNA
C.negative strand single-piece RNA
D.positive strand single-piece RNA
E.double-stranded RNA
12. The nucleocapsid of an enveloped virus was found to have 20 capsomers per face. How many capsomers total are there in each particle?
A. 200
B. About 2000
C. 400
D. About 4000
E. One can’t say, because the envelope size varies substantially for particles of any particular enveloped virus.
6. 5'-ctaagcgg-3' is part of a virus's ssDNA(+) genome. Imagine that this genome is converted to the ssDNA(-) during the infectious cycle. Write the ssDNA(-) equivalent of the above sequence-be sure to label 5' and 3' ends.
17. In the biology of influenza, what is responsible for the phenomenon of "antigenic drift"?
18a. If antigenic drift were to suddenly disappear, would flu vaccinations still be required every year? Why or why not?
1. Starting with binding to the host cell surface, draw the
infection cycle of influenza A. End with virus release from
the host, and be sure to include synthesis of viral mRNA and
viral proteins.
14. In class we discussed virus from the Herpes family. What do viruses in that family have in common?
A. Infection with any family member always results in serious symptoms
B. They all have dsDNA genomes
C. They all reside as latent particles in the host and can cause disease symptoms long after the initial infection
D. Two of the above are correct
E. Three of the above are correct
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15. Which of the diseases listed below is not a result of infection by a member of the Herpes family?
A. Cold sores
B. Shingles
C. Chicken pox
D. Roseola (also known as sixth disease)
E. All of the above are caused by Herpes viruses
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16. In class we discussed viral hepatitis. Which statement about viral hepatitis is not true.
A. It is always caused by enveloped viruses with ssDNA genomes
B. It is an infection of the liver
C. It is can passed by blood or intimate contact
D. It can be deadly
E. It can be mild
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17. HIV is a retrovirus, and many of the earliest anti-HIV drugs targeted reverse transcriptase. What does reverse transcriptase do?
A. Make DNA, using RNA as template
B. Make ssRNA(+) using ssRNA(-) as a template
C. Make ssRNA(-) using ssRNA(+) as a template
D. Make RNA, using DNA as template
E. All of the above
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18. Which of the following molecules act as a host-cell receptor for HIV?
A. CD4
B. CCR5
C. AIDS docking complex
D. CD4 and CCR5
E. AIDS docking complex and CCR5
21. Consider the following segment of ssRNA(-): 5'-GUUAACGGCA-3' . What would be the linear sequence of its corresponding ssRNA(+) version?
A. 5’-CAAUUGCCGU-3’
B. 3’-GUUAACGGCA-5’
C. 5'-GUUAACGGCA-3'
D. 3’-CAAUUGCCGU-5’
E. 5’-None of the above-3’
23. Once infected with Herpes Simplex 1 (HSV1) cold-sores tend to reappear in the same place on a regular basis. Why?
A. Because cold sores tend to reappear when lips become dry and chapped during winter.
B. Because the cells at that site have many viral receptors after the initial infection
C. Because the virus makes the site inaccessible to the immune system, and the site is then unprotected and open to re-infection
D. Because the virus takes up residence in nerve ganglions and follows nerves back to the site of infection
28. Which of the following statements about Hepatitis B virus and HIV are true?
A. Both have genomes consisting of DNA.
B. Both are transmitted by the similar types of "lifestyle practices"
C. Neither is problematic in developed countries
D. Effective vaccinations are currently available for both.
E. None of the statements are true
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Multiple Choice
Identify the choice that best completes the statement or answers the question.
____1.The destruction of cells as a result of viral lysis can be observed as a:
a. / tissue culture / d. / plaqueb. / lawn / e. / host
c. / soft agar
____3.An icosahedral capsid has how many sides?
a. / 4 / d. / 10b. / 6 / e. / 20
c. / 8
____4.In bacteriophage T4, the DNA genome is contained in the head, and binding to the host is facilitated by attachment of the:
a. / capsid / d. / envelopeb. / neck / e. / tegument
c. / tail fibers
____6.The genome of ______ssRNA viruses can serve directly as mRNA.
a. / positive-sense (+) / d. / double-strandedb. / negative-sense (–) / e. / prion
c. / all
____8.What happens to the virus protein coat when a bacterial cell is infected?
a. / It enters the host cell with the viral genome.b. / It remains on the outside of the host cell.
c. / It enters the host cell separately from the viral genome.
d. / It is released to attach to and inject another host cell.
e. / It becomes part of the host cell membrane.
____11.A key factor in the evolution of killer strains of influenza is that they:
a. / only have eight genes / d. / have a segmented genomeb. / have an RNA genome / e. / have a circular chromosome
c. / contain reverse transcriptase
____16.The influenza reassortment process is enhanced by a particular feature of the virus, namely the ______genome.
a. / linear / d. / single-strandedb. / circular / e. / segmented
c. / double-stranded
____18.Which antiviral agent is currently used to treat influenza infections targeting viral neuraminidase?
a. / Tamiflu / d. / Acyclovirb. / Pleconaril / e. / Vitravene
c. / Zidovudine
____19.The ______virus envelope proteins recognize the specific protein sequence of CD4 and CCR5 in order to attach and enter the host cell.
a. / HIV / d. / M13b. / influenza / e. / polio
c. / T4
____20.The causative agent of chickenpox is:
a. / herpes simplex virus 1 / d. / Epstein-Barr virusb. / herpes simplex virus 2 / e. / HIV
c. / varicella-zoster virus
____21.Which of the following best describes the genome of the influenza virus?
a. / negative-strand segmented RNA / d. / positive-strand single-piece RNAb. / positive-strand segmented RNA / e. / double-stranded RNA
c. / negative-strand single-piece RNA
____23.Some people are resistant to HIV infection because they:
a. / lack CD4 receptors on their macrophagesb. / lack CCR5 receptors on their macrophages
c. / lack macrophages
d. / produce proteases that destroy HIV
e. / all of the above
Short Answer
1.What are prions and how do they cause disease?
2.What is the viral envelope composed of? How does it differ from the bacterial cell envelope?
4.Some viruses require an RNA-dependent RNA polymerase. What does that mean? Using the same vernacular, what would you call the host cell RNA polymerase (RNA pol)? What would you call reverse transcriptase (RTase)?
5.Why do many RNA viruses encode their own RNA-dependent RNA polymerase and package them in viral particles?
12. The nucleocapsid of an enveloped virus was found to have 20 capsomers per face. How many capsomers total are there in each particle?
A. 200
B. About 2000
C. 400
D. About 4000
E. One can’t say, because the envelope size varies substantially for particles of any particular enveloped virus.
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13. Which of the following protein types are always found on the surface of virus particles?
A. Ribosomal proteins
B. Host antibodies
C. Polymerases
D. Proteins that bind to host receptors
E. Two of the above
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14. In class we discussed virus from the Herpes family. What do viruses in that family have in common?
A. Infection with any family member always results in serious symptoms
B. They all have dsDNA genomes
C. They all reside as latent particles in the host and can cause disease symptoms long after the initial infection
D. Two of the above are correct
E. Three of the above are correct
------
15. Which of the diseases listed below is not a result of infection by a member of the Herpes family?
A. Cold sores
B. Shingles
C. Chicken pox
D. Roseola (also known as sixth disease)
E. All of the above are caused by Herpes viruses
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16. In class we discussed viral hepatitis. Which statement about viral hepatitis is not true.
A. It is always caused by enveloped viruses with ssDNA genomes
B. It is an infection of the liver
C. It is can passed by blood or intimate contact
D. It can be deadly
E. It can be mild
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17. HIV is a retrovirus, and many of the earliest anti-HIV drugs targeted reverse transcriptase. What does reverse transcriptase do?
A. Make DNA, using RNA as template
B. Make ssRNA(+) using ssRNA(-) as a template
C. Make ssRNA(-) using ssRNA(+) as a template
D. Make RNA, using DNA as template
E. All of the above
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18. Which of the following molecules act as a host-cell receptor for HIV?
A. CD4
B. CCR5
C. AIDS docking complex
D. CD4 and CCR5
E. AIDS docking complex and CCR5
28. Which of the following statements about Hepatitis B virus and HIV are true?
A. Both have genomes consisting of DNA.
B. Both are transmitted by the similar types of "lifestyle practices"
C. Neither is problematic in developed countries
D. Effective vaccinations are currently available for both.
E. None of the statements are true
7. New influenza pandemics are often associated with “antigenic shifts”. For example, the 1933 H2N2 virus was replaced in 1968 by an H3N2 influenza strain. Why is it that influenza is particularly likely to undergo such antigenic shifts? Check the most important reason from the list below:
A) It has a segmented genome.
B) It has an RNA genome.
C) RNA dependent RNA-polymerizes are especially error prone.
D) The HA molecule may not be cleaved properly during infection.
8. Which of the following statements about viruses is false? (Choose E if all are correct).
A. Viruses are unable to replicate on their own
B. Viruses can sometimes be treated with penicillin
C. Viruses can cause some types of cancer
D. Viruses do not always kill their host cells
E. All of the above are true
9. Influenza type H5N1 (avian flu) is a growing concern. The virus can infect humans, but not easily. What are the main worries about this virus?
A. That it will gain mutations that allow it to easily infect and replicate in humans.
B. That it will undergo genetic shift.
C. That it will be accidentally released from laboratory settings
D. Two of the above
E. A, B, and C are all correct.
11. What is meant by “antigenic drift” in influenza biology? Pick one.
A) The slow spread of viral infection in crowded environments.
B) Changes in viral proteins and their genes by mutation.
C) The production of new hybrid viral particles following the infection of a single cell by two viral types
D) The spread of viral infection on a global scale like that which happened in 1918.
12. Viruses with single-stranded RNA as their genome, and for which the base sequence of that RNA is the same as the viral mRNA are said to be ______viruses.
A) minus-stranded
B) mRNA-like
C) plus-stranded
D) reverse-transcribed
13. Viral genomes come in a variety of types. Which of the types of nucleic acids listed below are always present as part of a virus's genome?
A. ssRNA(-)
B. ssDNA(+)
C. ssRNA(+)
D. dsDNA
E. None of the above
14. Which of the following statements about H1N1 influenza are true?
A) H1N1 is in circulation today
B) The hemagglutin protein is identical to the neuraminidase protein because each is a subtype 1
C) The hemagglutin protein and the neuraminidase protein are encoded on RNA genome segment “1” in H1N1
D) Two of the above are correct
E) A, B and C are correct
15. Consider the following bit of viral genome that is ssRNA(-):
5'-AUC CCG GUU AAA-3'. If you were going to figure out the sequence of the viral protein that is encoded by this bit of genome, your first job would be to figure out the proper codons. In this case, what are they?
A. 5'-AUC CCG UUG AAA-3'
B. 5'-AAA UUG GCC CUA-3'
C. 5'-UAG GGC CAA UUU-3'
D. 5'-UUU AAC CGG GAU-3'
E. None of the above, viruses with (-) genomes do not synthesize proteins.
16. Viruses that posses glycoprotein spikes acquire them
A) as they exit the nuclear membrane of the host cell.
B) as they exit the cell membrane of the host cell.
C) during capsid assembly.
D) in the cytoplasm of the host cell.
E) Both a and b
19. Which of the diseases listed below is not a result of infection by a member of the Herpes family?
A. Cold sores
B. Infectious mononucleosis
C. Chicken pox
D. Hepatitis
E. All of the above are caused by Herpes viruses
20. HIV is a retrovirus, and many of the earliest anti-HIV drugs targeted reverse transcriptase. What does reverse transcriptase do?
A. Make DNA, using RNA as template
B. Make ssRNA(+) using ssRNA(-) as a template
C. Make ssRNA(-) using ssRNA(+) as a template
D. Make RNA, using DNA as template
E. Make dsDNA using ssDNA as a template
21. Imagine that a new form of influenza A was found where all 8 of the genome segments, that are normally found in influenza, were fused into one long genome. Which of the following statements about the new type of influenza would you expect to be true?
A) The virus would be more variable because the RNA polymerase would be copying longer pieces of RNA
B) The virus could undergo antigenic shift
C) The virus could not undergo antigenic shift
D) The virus would be more likely to undergo antigenic drift
E) The virus would be less likely to undergo antigenic drift
22. In class we discussed viral hepatitis. Which statement about viral hepatitis is not true (or choose E if all are true).
A. It is always caused by enveloped viruses with RNA(+) genomes
B. It is an infection of the liver
C. It is can passed by blood or intimate contact
D. It can be mild