Question 1

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

Accepted Answer

A) True 
 B)False

Question 2

Would you expect the number of virions to be the same if you measured them by the plaque assay or by counting using the electron microscope? Why?

Accepted Answer

A)   Yes-both methods measure the total number of virus particles in a solution.
B)   No-the plaque assay only measures viable virus particles, while the electron microscope cannot distinguish between defective and viable virus.
C)   No-you cannot count virus particles by using a plaque assay. You can only get a relative difference in quantity from one preparation of virus particles to another with this method.
D)   Yes-only fully functioning viruses will be released from a host cell, so the quantified number of virus particles in a plaque assay should be identical to the number of free virus particles counted by electron microscopy within a given preparation.

Question 3

In the replication of phage containing positive-sense DNA,

Accepted Answer

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 4

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

Accepted Answer

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 5

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

Accepted Answer

A) True 
 B)False

Question 6

The best known chronic infection involves

Accepted Answer

A)   chickenpox.
B)   herpes.
C)   hepatitis A
D)   hepatitis B.

Question 7

The nucleocapsid is composed of

Accepted Answer

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 8

The changes that occur in virally-infected cells are characteristic for a particular virus and are referred to as the

Accepted Answer

A)   cytopathic effect.
B)   phenotypic effect.
C)   genotypic expression.
D)   cytology.

Question 9

Viruses are commonly referred to by their _________ name.

Accepted Answer

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

Question 10

Plant viruses enter the host plant via

Accepted Answer

A)   wound sites.
B)   specific receptors.
C)   nonspecific receptors.
D)   seeds.

Question 11

Once inside the host cell, phage DNA

Accepted Answer

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

Question 12

What part of the

Accepted Answer

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 13

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

Accepted Answer

A) True 
 B)False

Question 14

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

Accepted Answer

A) True 
 B)False

Question 15

RNA phages usually contain

Accepted Answer

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

Question 16

Which is a filamentous phage?

Accepted Answer

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

Question 17

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

Accepted Answer

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

Question 18

Why is it not surprising that AIDS patients frequently suffer a viral-induced tumor?

Accepted Answer

A)   HIV genomes integrate into the host cell chromosome. This integration might result in loss of control of the cell cycle (also known as cancer) .
B)   The immune system's CD4+ T cells are directly responsible for elimination of tumor cells. HIV attacks them and eliminates them, making a person more susceptible to cancer.
C)   The therapies for HIV are highly mutagenic, which may lead to cancerous states in people taking the drug regimen.
D)   Products of an active HIV infection are highly mutagenic-so, as a person's illness progresses, these mutagenic compounds build up and are more capable of inducing a cancerous state.

Question 19

Retroviruses are unique in that they

Accepted Answer

A)   replicate in nervous system cells.
B)   do not have a capsid.
C)   use RNA as a template to make DNA.
D)   use DNA as a template to make RNA.

Question 20

Transduction often involves defective virus.

Accepted Answer

A) True 
 B)False

Exam 13: Viruses, Viroids and Prions

Once inside the host cell, phage DNA

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The best known chronic infection involves

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Transduction often involves defective virus.

Correct AnswerverifiedShow Answer

What part of the

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which is a filamentous phage?

Correct AnswerverifiedShow Answer

RNA phages usually contain

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Would you expect the number of virions to be the same if you measured them by the plaque assay or by counting using the electron microscope? Why?

Correct AnswerverifiedShow Answer

Plant viruses enter the host plant via

Correct AnswerverifiedShow Answer

Viruses are commonly referred to by their _________ name.

Correct AnswerverifiedShow Answer

The changes that occur in virally-infected cells are characteristic for a particular virus and are referred to as the

Correct AnswerverifiedShow Answer

In the replication of phage containing positive-sense DNA,

Correct AnswerverifiedShow Answer

Why is it not surprising that AIDS patients frequently suffer a viral-induced tumor?

Correct AnswerverifiedShow Answer

The nucleocapsid is composed of

Correct AnswerverifiedShow Answer

Retroviruses are unique in that they

Correct AnswerverifiedShow Answer

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