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Flashcards in Viruses [2] Deck (18):
1

Most known plant viruses have ________-strand RNA genomes, because small genomes ________.
Most known plant viruses have ________-strand RNA genomes, because small genomes ________.
A: positive / interact more readily with host DNA
B: negative / interact more readily with host DNA
C: positive / facilitate cell-to-cell transfer
D: negative / facilitate cell-to-cell transfer

C

2

What is unusual about phage MS2 infection of Escherichia coli?
A: It enters through a host cell porin.
B: All proteins are synthesized simultaneously during infection so there are no early and late proteins.
C: More than one MS2 phage can be present in an individual E. coli cell.
D: It attaches to the host's pilus rather than the cell's surface.

D

3

Based on its function, which type(s) of viruses likely contain(s) a gene encoding for RNA replicase?
A: dsDNA and ssDNA viruses
B: positive ssRNA viruses
C: positive and negative ssRNA viruses
D: ssRNA and ssDNA viruses

C

4

Polyproteins made from human viruses such as poliovirus must be ________ in order to yield the required functional units of the virus.
A: post-translationally cleaved
B: properly folded into secondary and tertiary structures
C: able to interact with VPg proteins
D: chemically modified with either glycolation or methylation

A

5

What is the purpose of synthesizing a negative strand RNA in positive stranded ssRNA viruses?
A: enable transcription of genes occurring on both the negative and positive strands of the genome, such as overlapping genes
B: enable rolling circle amplification of the genome, which requires both strands of RNA
C: to serve as the complementary template sequence in genome amplification of the positive strand
D: proofreading of the genome to minimize mutations generated by the polymerase being passed onto virion progeny

C

6

Among the largest RNA genome viruses are ________ which contain a ________ genome.
A: coronaviruses / dsRNA
B: coronaviruses / positive ssRNA
C: polioviruses / dsRNA
D: polioviruses / positive ssRNA

B

7

Identifying proteases being essential for replication of a virus would suggest the virus
A: uses at least one set of overlapping genes.
B: lyses its host following genome replication.
C: contains at least one polyprotein.
D: has a single-stranded RNA genome.

C

8

Because the influenza virus is segmented, when two different strains infect the same cell, a major change in the virus can occur that is called __________.
A: viral mutation
B: hybridization
C: antigenic drift
D: antigenic shift

D

9

The hepadnavirus DNA polymerase acts as which of the following?
A: protein primer for synthesis of a strand of DNA
B: reverse transcriptase
C: DNA polymerase
D: DNA polymerase, reverse transcriptase, and protein primer for DNA synthesis

D

10

A drug designed to inhibit reverse transcriptase activity would target
A: viruses with RNA genomes.
B: hepadnaviruses and retroviruses.
C: coronaviruses and rhabdoviruses.
D: retroviruses.

B

11

In contrast to positive ssRNA viruses such as coronaviruses and polioviruses, the genome of retroviruses
A: lacks ribonuclease activity.
B: must first integrate into the host's genome before transcription.
C: is negative ssRNA.
D: lacks genes encoding for tRNA primers.

B

12

Proteins made by a ribosome reading through a transcript's stop codon without their own discrete ribosome binding sites
A: suggest a relatively low level of protein product is essential for the virus due to its rare frequency.
B: are thought to be a primitive mechanism to avoid host defenses.
C: appear most abundant in archaeal viruses and relatively uncommon in bacteriophage.
D: create opportunities for viruses to make different capsid proteins.

A

13

Explain why viroids can only infect and damage plant cells, but not animal cells.
A: Although both types of cells contain RNA, viroids recognize a specific receptor on the surface of plant cells.
B: Plant cells contain a RNA polymerase that can copy RNA can animal cells do not.
C: Animal cells contain RNA polymerase that can copy RNA and plant cells do not.
D: The genome of plant cells is made of RNA while animal cells have a DNA genome.

B

14


Which statement describes the difference between the normal neuron protein PrPC and the pathogenic version PrPSc?
A: The three-dimensional conformation is identical, but the amino acid sequence is different.
B: PrPC is just a protein and the PrPSc is a protein with nucleic acid inside.
C: The amino acid sequence is identical, but the three-dimensional conformation is different.
D: The PrPC protein contains more beta sheets while the PrPSc protein contains more alpha helices.

C

15

Retroviruses mutate relatively rapidly. What is one of the reasons?
A: Because retroviruses have multiple enzymes (reverse transcriptase, protease, and integrase), there is more opportunity for error.
B: Reverse transcriptase lacks the proofreading function found in many DNA polymerases, so mutations accumulate more easily.
C: Damage to the reverse transcriptase and other enzymes can lead to increased mutation rates.
D: Retroviruses have a lysogenic life cycle and accumulate mutations while within the host chromosome

B

16

How is penetration different in animal viruses as compared to bacterial viruses?
A: The viral genome penetrates an animal cell, while the entire viral particle penetrates a bacterial cell.
B: There is no difference; the entire viral particle penetrates both cell types.
C: There is no difference; only the viral genome penetrates both cell types.
D: The entire viral particle penetrates an animal cell, while only the viral genome penetrates a bacterial cell.

D

17

Differentiate between persistent and latent animal virus infections.
A: Persistent infections always lead to cell lysis, while latent infections never lead to cell lysis.
B: Persistent infections can cause transformation of the host cell, which can lead to the development of cancer. Latent infections do not cause transformation.
C: In a latent infection, the host cell is continually releasing new viral particles slowly. In a persistent infection, there are periods of time where the virus is not replicating and creating new viral particles.
D: In a persistent infection, the host cell is continually releasing new viral particles slowly. In a latent infection, there are periods of time where the virus is not replicating and creating new viral particles.

D

18

A retrovirus has a genome that consists of __________.
A: dsRNA
B: dsDNA
C: ssDNA
D: ssRNA

D
+ssRNA