Question 1

In a population of T4 virus, each virion has the same set of genes, but they are arranged in a different order.

Accepted Answer

A) True 
 B)False  TRUE

Question 2

In E. coli, the adenine in the sequence GATC is methylated by the Dam enzyme. In the same cells, a restriction endonuclease recognizes and cleaves dsDNA with the sequence GATC on either strand. Why does E. coli have these two enzymes?

Accepted Answer

A)  The enzymes cut the E. coli genome into pieces that bind to viral particles and inhibit viral replication. 
B)  The enzymes increase the rate of mutation and genome rearrangement, thus increasing the likelihood that E. coli cells will mutate and become resistant to viral infection. 
C)  The enzymes encourage lysogeny because the cleavage sites are recognized by viral integrases. 
D)  The enzymes protect E. coli from infection by preferentially degrading viral or other exogenous DNA that is not methylated. 
A)  The enzymes cut the E. coli genome into pieces that bind to viral particles and inhibit viral replication. 
B)  The enzymes increase the rate of mutation and genome rearrangement, thus increasing the likelihood that E. coli cells will mutate and become resistant to viral infection. 
C)  The enzymes encourage lysogeny because the cleavage sites are recognized by viral integrases. 
D)  The enzymes protect E. coli from infection by preferentially degrading viral or other exogenous DNA that is not methylated. D

Question 3

A cell that allows the complete replication cycle of a virus to take place is said to be a

Accepted Answer

A)  permissive host. 
B)  viral cell. 
C)  dead cell. 
D)  lytic cell. 
A)  permissive host. 
B)  viral cell. 
C)  dead cell. 
D)  lytic cell. A

Question 4

The majority of many important human viral diseases are caused by

Accepted Answer

A)  ssRNA viruses. 
B)  ds RNA viruses. 
C)  ss DNA viruses. 
D)  ds DNA viruses. 
A)  ssRNA viruses. 
B)  ds RNA viruses. 
C)  ss DNA viruses. 
D)  ds DNA viruses.

Question 5

RNA viruses encode host restriction systems designed to destroy host DNA.

Accepted Answer

A) True 
 B)False

Question 6

Explain why viruses are not considered to be living entities.

Accepted Answer

A virus consists of genetic material sur

Question 7

The HIV genome consists of

Accepted Answer

A)  a single ds RNA molecule. 
B)  two identical ssRNA molecules. 
C)  two identical ssDNA molecules. 
D)  a single DNA molecule. 
A)  a single ds RNA molecule. 
B)  two identical ssRNA molecules. 
C)  two identical ssDNA molecules. 
D)  a single DNA molecule.

Question 8

Temperate viruses can enter into either a lytic or lysogenic cycle.

Accepted Answer

A) True 
 B)False

Question 9

Viral replication occurs

Accepted Answer

A)  intracellularly. 
B)  extracellularly. 
C)  both intracellularly and extracellularly. 
D)  either intracellularly or extracellularly, depending on the virus involved. 
A)  intracellularly. 
B)  extracellularly. 
C)  both intracellularly and extracellularly. 
D)  either intracellularly or extracellularly, depending on the virus involved.

Question 10

The general steps of the viral lifecycle are similar in most viruses. One major exception, however, is entry into the host cell. How does this step differ between an animal cell and E coli?

Accepted Answer

A)  The entire virion is taken into an animal cell, but only the viral genome enters E coli. 
B)  The entire virion enters E coli, but only the nucleic acid is taken up by animal cells. 
C)  The virion fuses to the bacterial cell membrane of E coli, while the genome is injected into an animal cell. 
D)  The virion randomly attaches to E coli, but viral binding to a specific receptor is required for entry into animal cells. 
A)  The entire virion is taken into an animal cell, but only the viral genome enters E coli. 
B)  The entire virion enters E coli, but only the nucleic acid is taken up by animal cells. 
C)  The virion fuses to the bacterial cell membrane of E coli, while the genome is injected into an animal cell. 
D)  The virion randomly attaches to E coli, but viral binding to a specific receptor is required for entry into animal cells.

Question 11

In prokaryotes, DNA viruses replicate their genomes in the nucleus while RNA viruses are replicated in the cytoplasm.

Accepted Answer

A) True 
 B)False

Question 12

Prophage formation occurs after lambda infection if

Accepted Answer

A)  the cI gene is transcribed and cI protein accumulates. 
B)  cII expression occurs. 
C)  Cro accumulates in the cell. 
D)  both Cro and cI are equally activated. 
A)  the cI gene is transcribed and cI protein accumulates. 
B)  cII expression occurs. 
C)  Cro accumulates in the cell. 
D)  both Cro and cI are equally activated.

Question 13

Which of the following are the hosts for most enveloped viruses?

Accepted Answer

A)  Bacteria 
B)  animals 
C)  Archaea 
D)  fungi 
A)  Bacteria 
B)  animals 
C)  Archaea 
D)  fungi

Question 14

Rolling circle replication of the lambda genome differs from replication of a bacterial chromosome in that

Accepted Answer

A)  bidirectional replication forks are not formed. 
B)  only a single strand of the genome is copied. 
C)  no concatamers are formed. 
D)  only a single strand of the genome is copied and no concatamers are formed. 
A)  bidirectional replication forks are not formed. 
B)  only a single strand of the genome is copied. 
C)  no concatamers are formed. 
D)  only a single strand of the genome is copied and no concatamers are formed.

Question 15

Relate the structure of bacteriophages and animal viruses to the structure of their respective host cells and the steps of the viral life cycle.

Accepted Answer

The T4 phage has a very complex structur

Question 16

A prophage replicates

Accepted Answer

A)  along with its host while the lytic genes are expressed. 
B)  along with its host while the lytic genes are not expressed. 
C)  independently of its host while the lytic genes are expressed. 
D)  independently of its host while the lytic genes are not expressed. 
A)  along with its host while the lytic genes are expressed. 
B)  along with its host while the lytic genes are not expressed. 
C)  independently of its host while the lytic genes are expressed. 
D)  independently of its host while the lytic genes are not expressed.

Question 17

Explain why some viruses contain enzymes within the virion and others do not. Use specific examples to support your answer.

Accepted Answer

Viruses do not carry out metabolic proce

Question 18

How does plating efficiency affect the number of plaque-forming units? How is plating efficiency calculated?

Accepted Answer

The issue of plating efficiency is that

Question 19

Accumulation of the cI protein results in integration of the lambda genome and prophage formation.

Accepted Answer

A) True 
 B)False

Question 20

Rod-shaped viruses have icosahedral symmetry while spherical viruses have helical symmetry.

Accepted Answer

A) True 
 B)False

Exam 8: Viruses and Their Replication

In a population of T4 virus, each virion has the same set of genes, but they are arranged in a different order.

In E. coli, the adenine in the sequence GATC is methylated by the Dam enzyme. In the same cells, a restriction endonuclease recognizes and cleaves dsDNA with the sequence GATC on either strand. Why does E. coli have these two enzymes?

A cell that allows the complete replication cycle of a virus to take place is said to be a

The majority of many important human viral diseases are caused by

RNA viruses encode host restriction systems designed to destroy host DNA.

Explain why viruses are not considered to be living entities.

The HIV genome consists of

Temperate viruses can enter into either a lytic or lysogenic cycle.

Viral replication occurs

The general steps of the viral lifecycle are similar in most viruses. One major exception, however, is entry into the host cell. How does this step differ between an animal cell and E coli?

In prokaryotes, DNA viruses replicate their genomes in the nucleus while RNA viruses are replicated in the cytoplasm.

Prophage formation occurs after lambda infection if

Which of the following are the hosts for most enveloped viruses?

Rolling circle replication of the lambda genome differs from replication of a bacterial chromosome in that

Relate the structure of bacteriophages and animal viruses to the structure of their respective host cells and the steps of the viral life cycle.

A prophage replicates

Explain why some viruses contain enzymes within the virion and others do not. Use specific examples to support your answer.

How does plating efficiency affect the number of plaque-forming units? How is plating efficiency calculated?

Accumulation of the cI protein results in integration of the lambda genome and prophage formation.

Rod-shaped viruses have icosahedral symmetry while spherical viruses have helical symmetry.

The Microbial World

Microbial Cell Structure and Function

Microbial Metabolism

Molecular Information Flow and Protein Processing

Microbial Growth and Its Control

Microbial Regulatory Systems

Molecular Biology of Microbial Growth

Microbial Systems Biology

Viral Genomics, Diversity, and Ecology

Genetics of Bacteria and Archaea

Biotechnology and Synthetic Biology

Microbial Evolution and Systematics

Metabolic Diversity of Microorganisms

Functional Diversity of Microorganisms

Diversity of Bacteria

Diversity of Archaea

Diversity of Microbial Eukarya

Taking the Measure of Microbial Systems

Microbial Ecosystems

Nutrient Cycles

Microbiology of the Built Environment

Microbial Symbioses

Microbial Symbioses with Humans

Microbial Infection and Pathogenesis

Innate Immunity: Broadly Specific Host Defenses

Adaptive Immunity: Highly Specific Host Defenses

Clinical Microbiology and Immunology

Epidemiology

Person-to-Person Bacterial and Viral Diseases

Vectorborne and Soilborne Bacterial and Viral Diseases

Waterborne and Foodborne Bacterial and Viral Diseases

Eukaryotic Pathogens: Fungi, Protozoans, and Helminths

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