Deck 17: Genetics of Viruses

Question 1

Azidothymidine (AZT) is mentioned in your book as 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

Answer 1

B

Question 2

In phage $\lambda$ , the relative affinities of the lambda repressor and the cro protein to the three binding sites in the O_R region are:

A)the same.
B)inversely proportional.
C)unrelated.

Answer 2

inversely proportional.

Question 3

Reverse transcriptase copies

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

Answer 3

C

Question 4

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

Question 5

A bacteriophage that is physically integrated into the host chromosome is called a _______.

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

Question 6

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

Question 7

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.

Question 8

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

Question 9

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

Question 10

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

Question 11

When phage $\lambda$ 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.

Question 12

If you created a strain of bacteria that overexpressed protease inhibitors, and then infected this bacteria with phage $\lambda$ , 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.

Question 13

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

A) virulent phage
B) temperate phage
C) bacteria
D) eukaryotic cell

Question 14

The reverse transcription of HIV RNA utilizes host cell tRNA as a primer. Specifically, a tRNA for lysine is utilized. Would a drug that blocked the host cell synthesis of the tRNA for lysine be a good drug to prevent the HIV life cycle?

A)Yes, it should stop the reverse transcription of the HIV genome with few side effects.
B)No, the virus would just use a different tRNA for priming.
C)No, this would likely kill the cells that were drug treated, because they couldn't appropriately incorporate lysine into their proteins.
D)No, the priming function of the tRNA is not essential for the HIV life cycle.

Question 15

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

Question 16

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.

Question 17

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

A) virulent phage
B) temperate phage
C) bacteria
D) eukaryotic cell

Question 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

Question 19

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.

Question 20

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

Question 21

What structure on bacteriophage $\lambda$ plays an analogous role to the spike glycoproteins in HIV?

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

Question 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

Question 23

The ________ is an enveloped virus with spikes.

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

Question 24

Tetherin is a protein encoded in the human genome. Based on what you know about the interaction between Vpu and tetherin, what do you predict the broad cellular function of tetherin is?

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

Question 25

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