Ch18 Genetics of Viruses – Test Bank | 7th Edition

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1) Select the viruses that can infect humans. (Check all that apply.)

A) Tobacco mosaic virus
B) Baculovirus
C) Parvovirus
D) Influenza virus
E) Epstein-Barr virus
F) Adenovirus

2) Select all features that are true about emerging viruses. (Check all that apply.)

A) They are viruses that are not particularly dangerous.
B) They are more likely to cause infections than previous strains.
C) They often arise as a result of mutations.
D) H1N1 influenza, SARS, and HIV are examples.
E) Healthy people do not contract them.
F) Some emerging viruses began as viruses that infected other species.

3) Select the phage λ proteins that function as antiterminators. (Check all that apply.)

A) cII
B) N
C) Q
D) cro

4) A bacteriophage that is physically integrated into the host chromosome is called a __________.

A) episome
B) virulent phage
C) prophage
D) capsid

5) A _______ uses the lytic cycle to begin the immediate production of new phages in the host cells.

A) virulent phage
B) temperatephage
C) bacterium
D) eukaryoticcell

6) A _______ frequently integrates into the host genome, forming prophages and utilizing a lysogenic cycle to manufacture new phages.

A) virulent phage
B) temperatephage
C) bacteria
D) eukaryoticcell

7) Infectious mononucleosis is caused by the Epstein-Barr virus, and patients often exhibit a fever, sore throat, swollen glands, and fatigue for several weeks. In some patients, the virus can reactivate later and cause physical symptoms once again. This is likely because __________.

A) they were misdiagnosed the first time, and only really were infected by the virus the second time they became sick
B) the virus was latent in these patients, and then switched to the active form and began making new virus particles
C) the patients had the virus initially, and they became sick again at the time the virus became latent
D) the Epstein-Barr virus is an emerging virus so we do not know much about its infectious life cycle

8) Latency in HIV occurs when __________.

A) the virus switches back to an active form
B) new viral particles are made
C) the viral genome forms an episome and remains dormant
D) the virus integrates into the host genome and remains dormant

9) The HIV genome is especially prone to mutation because __________.

A) it is made of DNA
B) it is an emerging virus
C) it is copied by reverse transcriptase, which lacks a proofreading function
D) of the many different drugs HIV patients must take

10) When phage λ enters the lytic cycle

A) many new copies of the phage genetic material and coat proteins are assembled to make new phages. The host cell is lysed.
B) many new copies of the phage genetic material and coat proteins are assembled to make new phages. The host cell remains intact.
C) the genetic material of the phage is integrated into the chromosome of the bacterium.
D) it immediately lyses the host cells without producing any new viruses.

11) If you created a strain of bacteria that overexpressed protease inhibitors, and then infected this bacteria with phage λ, would you expect the phage to follow the lytic or lysogenic cycle?

A) Lytic
B) Lysogenic
C) The protease inhibitors would have no bearing on which life cycle is chosen.

12) Many scientists and drug companies have worked hard to produce drugs to stop various stages of the HIV life cycle. Some drugs have been tested that inhibit the function of Vpu. What stage of the HIV life cycle would such a drug inhibit?

A) Synthesis of double stranded DNA
B) Virus assembly
C) Virus budding
D) Integration into the host chromosome

13) The Gag polyprotein is cleaved into __________.

A) Vif and Vpu
B) HIV protease, reverse transcriptase, and integrase
C) matrix protein, capsid protein, nucleocapsid protein, and p6
D) Vpr, Rev, Tat, and Nef

14) Vaccines have been very useful in preventing viral diseases. In fact they have lead to the erradication of small pox from the world's human population. Most vaccines result in the host producing antibodies (proteins that bind to specific amino acid sequences) that bind to specific viral proteins. What might be a reason why a vaccine for HIV has been so difficult to develop?

A) The low mutation rate of HIV
B) The fact that HIV genome is found as both DNA and RNA in a cell
C) The high mutation rate of HIV
D) The HIV virion is coated with cellular proteins

15) What piece of the RNA HIV genome is used as a primer during the synthesis of double-stranded DNA from HIV RNA?

A) tRNA
B) U3
C) gag
D) PPT

16) Reverse transcriptase copies __________.

A) DNA to DNA
B) DNA to RNA
C) RNA to DNA
D) RNA to RNA

17) Gierer and Schramm isolated __________ from tobacco mosaic virus and applied it to plant tissue, which caused the same types of lesions that occurred when plants were exposed to intact tobacco mosaic virus.

A) RNA
B) DNA
C) proteins
D) capsids

18) You are working in a lab that studies tobacco mosaic virus (TMV). You wish to perform follow up experiments to the Fraenkel-Conrat/Singer experiments. You use the Holmes ribgrass (HR) strain of TMV that they used, which produces streaks along the veins and contains histidine and methionine in the TMV capsid protein. You also use a second TMV strain that you've isolated, called Purp, that causes purple lesions on the leaves, and lacks histidine and methionine in the TMV capsid protein. If you use Purp RNA and HR proteins to create reconstituted viruses, what lesions do you expect will form, and what will the amino acid composition of the capsid protein be?

A) Purple lesions, histidine and methionine in the capsid protein
B) Purple lesions, no histidine and methionine in the capsid protein
C) Streaks on the veins, no histidine and methionine in the capsid protein
D) Streaks on the veins, histidine and methionine in the capsid protein

19) What is the correct order of the reproductive cycle of viruses?

A) Attachment→Entry→Viral assembly→Integration→Synthesis of viral components→Release
B) Viral Assembly→Attachment-Entry-→Integration→Synthesis of viral components→Release
C) Attachment-→Entry→Integration→Synthesis of viral components→Viral assembly→Release
D) Integration→Attachment→Entry→Viral assembly→Synthesis of viral components→Release

20) In phage λ, the relative affinities of the lambda repressor and the cro protein to the three binding sites in the OR region are __________.

A) the same
B) inversely proportional
C) unrelated

21) Azidothymidine (AZT) is an HIV drug. AZT is a reverse transcriptase inhibitor. That means AZT is only effective during the __________ stage of the viral life cycle.

A) entry
B) integration
C) viral assembly
D) release

22) The virus that causes chickenpox can also cause __________ decades later when it switches from the latent state and starts making new viral particles.

A) shingles
B) herpes
C) cold sores
D) mononucleosis

23) The ________ is an enveloped virus with spikes.

A) tobacco mosaic virus
B) adenovirus
C) influenza virus
D) T4 bacteriophage

24) What structure on bacteriophage λ plays an analogous role to the spike glycoproteins in HIV?

A) Capsid
B) Shaft
C) Base plate
D) Tail fibers

25) What is the function of tetherin in HIV replication?

A) To keep HIV particles in place until they are ready to bud
B) To stop the spread of HIV in the body by inhibiting HIV release
C) To help in HIV assembly
D) To help with the maturation of HIV particles

26) Why is AZT (a nucleoside analog) able to suppress HIV infection but does not cure HIV infections?

A) It prevents viral budding but does not inhibit replication of viral nucleic acid.
B) It inhibits proviral replication but does not inhibit reverse transcritpase.
C) It prevents viral RNA from replicating but does not rid nuclear DNA of the provirus.
D) It stops proviruses in the nucleus from producing viral RNA but does not inhibit integration of viral DNA.

27) A researcher wishes to use the lambda phage promoter P Land operator in a synthetic gene they are creating. They want this to be an inducible transcript meaning that they would like to turn transcription on and off at will. What should they do?

A) They should create a cell in which they can turn cro expression on and off and place thier synthetic gene in the cell.
B) They should create a cell where they can turn expression of the Q gene on and off and then place their construct in the cell.
C) They should select a cell that lacks the att site to place their construct in.
D) They should create a cell that overexpresses the xis gene product.

28) A researcher has discovered a new compound that appears to affect the amount of HIV that they obtain from infecting cells. When cells are treated with the drug and then infected there are proviruses in the nuclear genome and viral RNA in the cytoplasm but no virus particles form. What is the most likely protein that the drug inhibits?

A) Spike protein
B) Reverse transcriptase
C) Gag proteins
D) Integrase

29) Most biologists consider viruses to be living organisms, which are classified with bacteria.

⊚ true
⊚ false

30) Because tobacco mosaic virus has an RNA genome, it must encode a reverse transcriptase.

⊚ true
⊚ false

31) The HIV genome contains nine genes and therefore encodes just nine proteins.

⊚ true
⊚ false

32) Both Phage Lambda and HIV use tail fibers to bind to their receptor proteins.

⊚ true
⊚ false

33) Since both Phage Lambda and HIV can integrate into a chromosome of the host cell, their viral genomes encode integrase.

⊚ true
⊚ false

34) Both Phage Lambda and HIV use reverse transcriptase.

⊚ true
⊚ false