Deck 13: Viruses, Viroids and Prions

Question 1

One of the most intensively studied virulent phages which infects

A) T9.
B) T4.
C) beta.
D) gamma.
E) coli is

Answer 1

B

Question 2

The protein projections on the surface of a virus that are involved in attachment to the host cell are called

A) suckers.
B) pili.
C) cilia.
D) spikes.
E) hooks.

Answer 2

D

Question 3

Outside of living cells, viruses are

A) scavenging glucose.
B) slowly stockpiling ATP from the mitochondria.
C) using cilia to move to the next host.
D) metabolically inert.

Answer 3

D

Question 4

Crystallization of Tobacco Mosaic Virus was accomplished by

A) Berkley.
B) Stanley.
C) Iwanowsky.
D) Twort.

Question 5

The correct order for the stages of a phage infection is:

A) penetration, transcription, attachment, replication of nucleic acid and protein, assembly, release
B) attachment, penetration, transcription, replication of nucleic acid and protein, assembly, release
C) attachment, replication of nucleic acid and protein, penetration, transcription, assembly, release
D) transcription, attachment replication of nucleic acid and protein, assembly, penetration, release

Question 6

Viruses that infect bacteria are referred to as

A) viralcidens.
B) bacteriocidins.
C) bacterialogens.
D) bacteriophages.

Question 7

A virion is a(n)

A) pathogenic virus.
B) subviral particle.
C) complete, extracellular virus particle.
D) enveloped virus particle.

Question 8

The shape of the virus is determined by its

A) nucleic acid.
B) capsid.
C) envelope.
D) tail.

Question 9

Viruses

A) probably keep the numbers of bacteria in check.
B) have no effect on the number of bacteria.
C) increase the number of bacteria.
D) are active in passing DNA from one bacterium to another.
E) probably keep the numbers of bacteria in check AND are active in passing DNA from one bacterium to another.

Question 10

What part of the

A) Capsid fragments around the nucleic acid.
B) Protein fibers at the end of the phage tail.
C) Pili of the envelope.
D) Spikes of the envelope.
E) coli T4 phage attaches to the host cell receptors?

Question 11

Which does not refer to the shape of a virus?

A) icosahedral (isometric)
B) helical
C) complex
D) bacillus

Question 12

During penetration of

A) lysozyme is used to allow entry of the phage capsid.
B) the tail acts as a "hypodermic needle", injecting the phage DNA into the cell.
C) the protein fibers digest a hole in the cell wall.
D) the bacterial receptor molecules open a hole through the cell wall.
E) coli by the T4 phage

Question 13

What part of the attached bacteriophage enters through the host cell wall?

A) the entire virus
B) only the enzymes necessary for replication
C) the nucleic acid
D) the nucleic acid and capsid
E) the capsid only

Question 14

Phages that can either replicate and cause cell lysis or can integrate their DNA into the host DNA are called

A) lysogenic phages.
B) lytic phages.
C) virulent phages.
D) segmented phages.

Question 15

The protein coat of a virus

A) is called a capsomere.
B) is called a capsid.
C) protects the nucleic acid.
D) is involved in recognition of host cell receptors.
E) is called a capsid, protects the nucleic acid AND is involved in recognition of host cell receptors.

Question 16

A phage that replicates inside the host cell and then lyses its host during its release is a

A) virulent or lytic phage.
B) latent phage.
C) lysogenic phage.
D) dormant phage.

Question 17

A virion is composed of

A) lipid, protein, and either RNA or DNA.
B) protein and either RNA or DNA.
C) protein and both, RNA and DNA.
D) protein, either RNA or DNA, and possibly lipid.

Question 18

The viral envelope closely resembles the

A) prokaryotic cell wall.
B) capsomere.
C) eukaryotic cell membrane.
D) cytoplasm.

Question 19

The term filterable viruses was coined by

A) Beijerinck.
B) Iwanowsky.
C) Twort.
D) d'Herelle.

Question 20

During attachment of phage to E. coli, the phage

A) actively seek out the bacteria.
B) randomly bump into the bacteria.
C) attach to proteins or carbohydrates on the bacterial surface.
D) attach to the bacterial RNA.
E) randomly bump into the bacteria AND attach to proteins or carbohydrates on the bacterial surface.

Question 21

Most phages that contain single-stranded DNA

A) are extruded.
B) contain a positive-sense DNA strand.
C) have their DNA transformed to double-stranded DNA before replication and transcription occur.
D) All of the choices are correct.

Question 22

The filamentous phages all contain

A) single-stranded DNA.
B) double-stranded DNA.
C) single-stranded RNA.
D) double-stranded RNA.

Question 23

In the case of T-even phages, the burst size is about

A) 1 per host cell.
B) 5 per host cell.
C) 200 per host cell.
D) 1000 per host cell.

Question 24

A temperate phage

A) may be lysogenic.
B) may be lytic.
C) enters a lysogenic or lytic life cycle shortly after entering the host cell.
D) are all RNA viruses.
E) may be lysogenic AND enters a lysogenic or lytic life cycle shortly after entering the host cell.

Question 25

Once integrated, phage DNA can remain in the prophage state as long as

A) the bacteria is frequently plated on new media.
B) certain phage genes are excised.
C) certain phage genes are repressed.
D) bacterial repressor genes are activated.

Question 26

RNA phages usually contain

A) dsRNA.
B) dsDNA.
C) ssRNA.
D) ssDNA.

Question 27

The activation of the SOS system in a bacterium infected with a prophage results in

A) destruction of the viral genes.
B) complete lysis of the bacterial culture.
C) mutation of the DNA.
D) destruction of the viral repressor through host protease activity.
E) complete lysis of the bacterial culture AND destruction of the viral repressor through host protease activity.

Question 28

In the replication of phage containing positive-sense DNA,

A) the host's enzymes are used to make dsDNA.
B) the host's DNA polymerase uses the phage RNA as a template to make negative-sense DNA.
C) a phage-encoded DNA polymerase is used to make negative-sense RNA using the phage positive-sense RNA as a template.
D) a phage-encoded DNA polymerase is used to make DNA using the phage positive-sense RNA as a template.

Question 29

Phage-encoded proteins are

A) coded for by host DNA.
B) coded for by phage DNA.
C) proteins normally present in the uninfected cell.
D) early proteins.
E) coded for by phage DNA AND early proteins.

Question 30

Regarding phage replication,

A) the majority of phages are temperate.
B) when integrated into host DNA, the phage DNA is called a prophage.
C) lambda is a good example of a temperate phage.
D) All of the choices are correct.

Question 31

The integration of phage DNA into the bacterial chromosome occurs because of

A) identical DNA sequences in both.
B) the phage's ability to synthesize enzymes to enter the bacterium.
C) similar RNA nucleotides in both.
D) the similarity in enzyme metabolism.
E) the phage's ability to synthesize enzymes to enter the bacterium AND similar RNA nucleotides in both.

Question 32

An exit method used by viruses which does not immediately destroy the host bacterium is

A) lysis.
B) inversion.
C) extrusion.
D) excising.

Question 33

Filamentous phage

A) only infect E. coli lacking pili.
B) only infect E. coli lacking pili.
C) infect E. coli regardless of the presence of pili.
D) do not infect

Question 34

Bacteria infected with filamentous phages are termed

A) temperate cells.
B) plaque-producing cells.
C) virulent strains.
D) carrier cells.

Question 35

Phage-encoded enzymes are

A) all produced simultaneously.
B) produced in a sequential manner.
C) strictly host enzymes.
D) used to customize the cell for viral production.
E) produced in a sequential manner AND used to customize the cell for viral production.

Question 36

The bacterial viruses that are released by a process termed extrusion are called

A) lysogenic viruses.
B) temperate phages.
C) filamentous phages.
D) lambda viruses.

Question 37

Assembly of the T4 phage

A) may involve some self-assembly.
B) may involve the use of scaffolds.
C) is completely self-assembly.
D) is completely dependent on scaffolds.
E) may involve some self-assembly AND may involve the use of scaffolds.

Question 38

The replicative form of nucleic acid in filamentous phages is

A) dsDNA.
B) dsRNA.
C) positive ssRNA.
D) negative ssDNA.

Question 39

Which is a filamentous phage?

A) M13
B) T4
C) lambda
D) phi X174

Question 40

The time from absorption to release for T-even phage is about

A) 1 minute.
B) 10 minutes.
C) 30 minutes.
D) 1 day.

Question 41

Filamentous virus is incapable of causing a lytic infection.

Question 42

All single-stranded DNA phages are extruded.

Question 43

Completed filamentous phages are often found in the cytoplasm of infected bacteria.

Question 44

Lysogenized cells

A) are immune to any further infection by any virus.
B) are immune to infection by the same virus.
C) may have new properties.
D) respond to infection with the SOS response.
E) are immune to infection by the same virus AND may have new properties.

Question 45

The host range of a virus depends on the presence of host receptor molecules.

Question 46

If the infecting phage lacks some critical pieces of DNA necessary for replication it is called

A) incomplete.
B) mutated.
C) defective.
D) vegetative.

Question 47

DNA is protected from restriction enzymes by being

A) sequestered in a lysosome.
B) turned into RNA.
C) methylated.
D) made into double stranded RNA.

Question 48

Using phages to treat a bacterial infection is an interesting idea because

A) a single type of phage can destroy a wide range of strains of the same pathogen.
B) of the increasing problem of antibiotic resistance.
C) lysed bacteria pose no threat.
D) a single phage can be genetically engineered to infect many different species of bacteria.

Question 49

The RNA phages contain only a single positive-sense strand of RNA.

Question 50

Transducing virulent phages do not lyse the cells they invade because

A) transformation is taking place in the phage and this is transferred to the bacterium.
B) bacterial DNA has replaced critical viral DNA in the phage.
C) their virulence is dependent on the bacteria and virus replicating together.
D) the lytic genes are unable to enter during penetration and are shed outside the host.

Question 51

Once inside the host cell, phage DNA

A) is replicated.
B) is transcribed.
C) may get degraded by bacterial nucleases.
D) All of the choices are correct.

Question 52

The phenomenon responsible for the ability of Corynebacterium diphtherium to produce the virulent toxin responsible for the devastating effects of diphtheria is called

A) self-assembly.
B) matrix conversion.
C) prion protein.
D) lysogenic conversion.

Question 53

Specialized transduction

A) involves the random transmission of any gene.
B) involves the transfer of a few specific genes.
C) utilizes a defective virus.
D) only involves genes near the viral DNA integration site.
E) involves the transfer of a few specific genes, utilizes a defective virus AND only involves genes near the viral DNA integration site.

Question 54

A lysogenic cell contains viral DNA, a prophage, integrated into the host chromosome.

Question 55

The nucleocapsid is composed of

A) DNA and RNA and protein.
B) DNA or RNA and protein.
C) protein located in the nucleus.
D) nucleic acid in the ribosome.

Question 56

The integration of phage DNA into host DNA occurs in much the same fashion as seen in transformation, transduction or conjugation.

Question 57

Virulent as well as temperate phages can serve as generalized transducing phages.

Question 58

The restriction-modification system always has two genes involved, the cutting enzyme and the methylating enzyme.

Question 59

Transduction often involves defective virus.

Question 60

A limiting factor for viral infection is

A) internal metabolic temperature of the host cell.
B) nutrition of the host cell.
C) stage of cell cycle of the host cell.
D) presence of specific receptor molecules on the host cell.

Question 61

The receptors to which animal virus attachment proteins usually bind are

A) proteins.
B) carbohydrates.
C) nucleic acid.
D) lipids.
E) glycoproteins.

Question 62

Viruses are commonly referred to by their _________ name.

A) locale
B) genus
C) disease
D) species
E) disease AND species

Question 63

There are _______ families of DNA containing viruses that infect vertebrates.

A) two
B) four
C) five
D) seven

Question 64

In addition to lysis, animal viruses may exit the host cell by

A) extrusion.
B) budding.
C) fission.
D) fusion.

Question 65

Resistance of some animals to certain viral diseases is based on

A) lack of spikes for attachment.
B) phagocytosis of the virus by the host cell.
C) the presence of the viral envelope.
D) lack of specific receptors on the host cell.

Question 66

The terms isometric, icosahedral and pleomorphic refer to

A) viral life cycles.
B) forms of nucleic acid.
C) types of viral envelopes.
D) shapes of viruses.

Question 67

Animal viruses are divided into a number of families whose names end in

A) -virus.
B) -viridae.
C) -viscous.
D) -eieio.

Question 68

When an enveloped virus adsorbs to the host cell with its protein spikes, the virions are taken into the cell by the process of

A) penetration.
B) production.
C) fusion.
D) endocytosis.

Question 69

In the region of budding, the inside of the plasma membrane becomes coated with

A) enzymes.
B) carbohydrates.
C) steroids.
D) matrix proteins.

Question 70

Enveloped viruses

A) just require a stamp.
B) have an outer lipid bilayer membrane containing various proteins.
C) are surrounded by an additional layer of carbohydrate.
D) envelope a cell.

Question 71

A key feature of all viral infections is the

A) integration of viral DNA into host DNA.
B) disintegration of host DNA.
C) addition of a lipid membrane to the virus.
D) separation of viral nucleic acid from the capsid.

Question 72

Cells infected with animal viruses lyse because

A) the release of the virions depletes the cell of energy.
B) the virus releases enzymes that lyse the cell.
C) functions necessary for cell survival are not carried out and the cell dies.
D) the virus RNA and cellular protein interact to kill the cell.

Question 73

Attachment of animal viruses to the host cell may be by means of

A) a tail.
B) the envelope.
C) a capsid.
D) spikes.

Question 74

The term "segmented" refers to viruses that

A) may contain several pieces of RNA.
B) have an icosahedral-shaped capsid.
C) are linked together before budding out.
D) have an envelope.

Question 75

The family to which the Rhinovirus belongs is the

A) Picornaviridae.
B) Enterovirus.
C) Enteroviridae.
D) Picornavirus.

Question 76

There are _______ families of RNA containing viruses that infect vertebrates.

A) two
B) five
C) seven
D) fourteen

Question 77

For which of the following processes are enzymes not required?

A) replication
B) translation
C) maturation
D) self-assembly

Question 78

Bacteriophages and animal viruses

A) both may enter a host cell by endocytosis.
B) both may enter a host cell by fusion.
C) both involve entry of the entire nucleocapsid.
D) differ because bacteriophages leave the capsid outside the cell, while animal virus entry involves the entry of the whole nucleocapsid.

Question 79

An infection in which the virus is continually present in the body is referred to as

A) acute.
B) balanced.
C) determinant.
D) persistent.

Question 80

The common species name of the virus is based on the

A) presence or absence of a nuclear membrane.
B) type of nucleic acid it contains.
C) disease the virus causes.
D) geographic area it is found.