Question 1

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 structure,containing a head,collar,tail,tail pins,an endplate,and tail fibers.The tail fibers bind to specific receptors on the surface of a bacterial cell (outside the peptidoglycan cell wall).When the tail fibers retract,the tail pins bind to the host so that the tail itself interacts with the cell wall.A viral enzyme then forms a small pore in the host cell wall.The tail's covering then contracts and inserts the virus into the host's cytoplasm.Animal viruses are usually much simpler in structure than bacteriophages because animal host cells lack a cell wall.Penetration is therefore somewhat easier and is usually accomplished by endocytosis or merging of the viral envelope with the host cell membrane.The complicated fibers and contractile tail are not needed to penetrate the animal cell.One last difference is that the entire virion often enters the animal cell and not just the viral genome.

Question 2

The growth of viruses in a culture is described as a one-step growth curve,because

Accepted Answer

A)  virion numbers show no increase during intracellular replication and can only be counted after the virions burst from the host cell. 
B)  there is only one step in the viral life cycle which leads to only one replicative cycle in a culture. 
C)  assembly and release actually occur in one step. 
D)  the eclipse phase prevents the plating and enumeration of virions although new virions are produced at a steady rate during the eclipse phase. 
A)  virion numbers show no increase during intracellular replication and can only be counted after the virions burst from the host cell. 
B)  there is only one step in the viral life cycle which leads to only one replicative cycle in a culture. 
C)  assembly and release actually occur in one step. 
D)  the eclipse phase prevents the plating and enumeration of virions although new virions are produced at a steady rate during the eclipse phase. A

Question 3

Which statement is TRUE?

Accepted Answer

A)  All viruses contain their own nucleic acid polymerases. 
B)  Many viruses contain their own nucleic acid polymerases. 
C)  Viruses do not contain their own nucleic acid polymerases. 
D)  The origins of the nucleic acid polymerases used by viruses are eukaryotic. 
A)  All viruses contain their own nucleic acid polymerases. 
B)  Many viruses contain their own nucleic acid polymerases. 
C)  Viruses do not contain their own nucleic acid polymerases. 
D)  The origins of the nucleic acid polymerases used by viruses are eukaryotic. B

Question 4

The virus repressor protein provides immunity to infection by the same type of virus.

Accepted Answer

A) True 
 B)False

Question 5

Viruses have both an intracellular and an extracellular form.

Accepted Answer

A) True 
 B)False

Question 6

In a natural population of diverse slow-growing prokaryotic cells,what type of viruses would you expect to be most common?

Accepted Answer

A)  lytic bacteriophages 
B)  enveloped viruses 
C)  icosahedral viruses 
D)  temperate bacteriophages 
A)  lytic bacteriophages 
B)  enveloped viruses 
C)  icosahedral viruses 
D)  temperate bacteriophages

Question 7

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 8

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

Accepted Answer

In the example of retroviruses,the rever

Question 9

The use of ________ is the easiest and most effective way of studying many animal and plant viruses.

Accepted Answer

A)  bacterial cultures 
B)  tissue or cell culture 
C)  live hosts 
D)  prophages 
A)  bacterial cultures 
B)  tissue or cell culture 
C)  live hosts 
D)  prophages

Question 10

In viruses,genetic information flows from ________ to ________.

Accepted Answer

A)  RNA / virion 
B)  nucleic acid / protein 
C)  capsid / virion 
D)  DNA / protein 
A)  RNA / virion 
B)  nucleic acid / protein 
C)  capsid / virion 
D)  DNA / protein

Question 11

Viruses can confer additional properties on their host cells,which can in turn be inherited.

Accepted Answer

A) True 
 B)False

Question 12

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

Accepted Answer

A) True 
 B)False

Question 13

You are attempting to mutate lambda to affect whether lysis or lysogeny occurs after lambda infection.Which mutation would INCREASE the chances of LYSOGENY over lysis?

Accepted Answer

A)  deletion or inactivation of the cI gene 
B)  deletion or inactivation of the cro gene 
C)  overexpression of the cro gene 
D)  deletion of both the cro and cI genes 
A)  deletion or inactivation of the cI gene 
B)  deletion or inactivation of the cro gene 
C)  overexpression of the cro gene 
D)  deletion of both the cro and cI genes

Question 14

Tailed bacterial viruses can be used as genetic engineering tools.

Accepted Answer

A) True 
 B)False

Question 15

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 16

Lysogeny is unique to bacteriophages; similar relationships have not been found among the animal viruses.

Accepted Answer

A) True 
 B)False

Question 17

Describe the establishment and maintenance of the lysogenic state in the lambda phage.

Accepted Answer

Lambda phage,once circularized by matchi

Question 18

The latent phase in the viral growth curve and the lag phase of the bacterial growth curve are equivalent and represent the time it takes for the virus or bacterium to adapt to the culture conditions and begin growing.

Accepted Answer

A) True 
 B)False

Question 19

Penetration requires that the entire virus is inserted within the host.

Accepted Answer

A) True 
 B)False

Question 20

Ocean and lake water typically contain 10⁷ virions/mL.Does this mean that swimming in or drinking this water will make you sick? Why or why not? How do these viruses impact human and environmental health?

Accepted Answer

Although there are many virions per mL o

Exam 8: Viruses and Virology

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

The growth of viruses in a culture is described as a one-step growth curve,because

Which statement is TRUE?

The virus repressor protein provides immunity to infection by the same type of virus.

Viruses have both an intracellular and an extracellular form.

In a natural population of diverse slow-growing prokaryotic cells,what type of viruses would you expect to be most common?

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

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

The use of ________ is the easiest and most effective way of studying many animal and plant viruses.

In viruses,genetic information flows from ________ to ________.

Viruses can confer additional properties on their host cells,which can in turn be inherited.

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

You are attempting to mutate lambda to affect whether lysis or lysogeny occurs after lambda infection.Which mutation would INCREASE the chances of LYSOGENY over lysis?

Tailed bacterial viruses can be used as genetic engineering tools.

Viral replication occurs

Lysogeny is unique to bacteriophages; similar relationships have not been found among the animal viruses.

Describe the establishment and maintenance of the lysogenic state in the lambda phage.

The latent phase in the viral growth curve and the lag phase of the bacterial growth curve are equivalent and represent the time it takes for the virus or bacterium to adapt to the culture conditions and begin growing.

Penetration requires that the entire virus is inserted within the host.

Ocean and lake water typically contain 10⁷ virions/mL.Does this mean that swimming in or drinking this water will make you sick? Why or why not? How do these viruses impact human and environmental health?

Microorganisms and Microbiology

Microbial Cell Structure and Function

Microbial Metabolism

Molecular Biology

Microbial Growth and Control

Microbial Genomics

Metabolic Regulation

Viral Genomes and Diversity

Genetics of Bacteria and Archaea

Genetic Engineering and Biotechnology

Microbial Evolution and Systematics

Metabolic Diversity of Microorganisms

Functional Diversity of Bacteria

Diversity of Bacteria

Diversity of Archaea

Diversity of Eukaryotic Microorganisms

Methods in Microbial Ecology

Microbial Ecosystems

Nutrient Cycles

Microbiology of the Built Environment

Microbial Symbioses

Microbial Interactions With Humans

Immunity and Host Defense

Immune Mechanisms

Molecular Immunology

Diagnostic Microbiology

Epidemiology

Person-To-Person Bacterial and Viral Diseases

Vectorborne and Soilborne Bacterial and Viral Diseases

Water and Food As Vehicles of Bacterial Diseases

Eukaryotic Pathogens: Fungal and Parasitic Diseases

Filters

In viruses,genetic information flows from to .