Question 1

Viruses that infect archaeal cells have been isolated from all of the following environments EXCEPT:

Accepted Answer

A) Hot springs with temperatures over 80oC 
B) Environments with a pH of 0 
C) Solfataric fields that emit sulfur gases 
D) The surface of the moon 
E) Environments with salt concentrations over 1.5M 
A) Hot springs with temperatures over 80oC 
B) Environments with a pH of 0 
C) Solfataric fields that emit sulfur gases 
D) The surface of the moon 
E) Environments with salt concentrations over 1.5M D

Question 2

In comparing the genomes of the viruses that infect archaeal cells,very few of the viral genomes have genes encoding an identifiable DNA polymerase.Give two possibilities that explain this observation.

Accepted Answer

One possibility is that these viruses do not encode their own DNA polymerase but instead use the DNA polymerases of their host cells to carry out the replication of their genomes.Instead of encoding a polymerase,they would encode unique viral protein that would just direct the host cell proteins to replicate the viral genome.This is similar to the mechanisms used by the smaller DNA viruses that infect eukaryotic cells,like parvoviruses,polyomaviruses and papillomaviruses.The second possibility is that they encode DNA polymerases that do not resemble known DNA polymerases based on amino acid sequence.This would make the function of the genes encoding these enzymes impossible to identify as DNA polymerases.

Question 3

Which of the following terms specifically describes archaeal organisms that can grow above 80oC?

Accepted Answer

A) Thermophile 
B) Hyperhalophile 
C) Hyperthermophile 
D) Methanogen 
E) Extremophile 
A) Thermophile 
B) Hyperhalophile 
C) Hyperthermophile 
D) Methanogen 
E) Extremophile C

Question 4

Infection of the archaeal cell Acidianus with the virus ATV at the suboptimal temperature of 75oC leads to a productive lytic infection rather than lysogeny.

Accepted Answer

A) True 
 B)False

Question 5

What is unusual about the virion of the Acidianus two-tailed virus?

Accepted Answer

A) The virion contains two tails,one at each end of a lemon-shaped virion. 
B) The two tails can be of different lengths. 
C) The only requirement for tail production is temperatures above 75oC. 
D) The tails are elongated after the virion leaves the host cell. 
E) All of the above are correct. 
A) The virion contains two tails,one at each end of a lemon-shaped virion. 
B) The two tails can be of different lengths. 
C) The only requirement for tail production is temperatures above 75oC. 
D) The tails are elongated after the virion leaves the host cell. 
E) All of the above are correct.

Question 6

The extrusion of the tails on the Acidianus two-tailed virus requires which of the following?

Accepted Answer

A) Temperatures above 75oC 
B) An exogenous source of energy 
C) Cofactors from the host cell 
D) Cofactors from the virus 
E) High salt concentration 
A) Temperatures above 75oC 
B) An exogenous source of energy 
C) Cofactors from the host cell 
D) Cofactors from the virus 
E) High salt concentration

Question 7

Which of the following can be found at the ends of the genome of a virus that infects archaeal cells?

Accepted Answer

A) Covalently bound protein 
B) Inverted terminal repeats 
C) Telomeric-like repeat sequences 
D) Covalently closed ends 
E) All of the above can be found. 
A) Covalently bound protein 
B) Inverted terminal repeats 
C) Telomeric-like repeat sequences 
D) Covalently closed ends 
E) All of the above can be found.

Question 8

Into which of the following genes in the host cell genome does the archaea virus SSV-1 integrate its genome?

Accepted Answer

A) DNA polymerase 
B) RNA polymerase 
C) Transfer RNA 
D) Translation initiation factor 
E) Ribosomal RNA 
A) DNA polymerase 
B) RNA polymerase 
C) Transfer RNA 
D) Translation initiation factor 
E) Ribosomal RNA

Question 9

Rudiviruses,a family of archaea viruses,are different from most other archaea viruses in that they lyse the host cell to release mature virions.

Accepted Answer

A) True 
 B)False

Question 10

Many of the viruses that infect archaeal cells primarily carry out a lysogenic infection.Even if they do enter a productive infectious cycle,they can release new virions without killing the host cell.What might be the evolutionary advantages of these lifestyle features?

Accepted Answer

The host cells for many of these archaea

Question 11

Archaea cells contain a nucleus like eukaryotic cells.

Accepted Answer

A) True 
 B)False

Question 12

Viruses that infect archaeal cells have been observed to have all of the following virion shapes EXCEPT:

Accepted Answer

A) Bottle shaped with a wide and a narrow end 
B) Spherical 
C) Brick shaped 
D) Filamentous 
E) Lemon-shaped 
A) Bottle shaped with a wide and a narrow end 
B) Spherical 
C) Brick shaped 
D) Filamentous 
E) Lemon-shaped

Question 13

What information was used to identify the three domains of life?

Accepted Answer

A) Sequence of the 16S ribosomal RNA 
B) Sequence of the mitochondrial genome 
C) Sequence of the cytochrome c gene 
D) Chemical structure of the cell wall 
E) Chemical structure of phospholipids 
A) Sequence of the 16S ribosomal RNA 
B) Sequence of the mitochondrial genome 
C) Sequence of the cytochrome c gene 
D) Chemical structure of the cell wall 
E) Chemical structure of phospholipids

Question 14

Even though the two archaeal viruses HHPV-1 and HRPV-1 are clearly related to each other,based on genome and virion structures,they have one major difference.Which of the following describes this difference?

Accepted Answer

A) One can undergo lysogeny while the other can only carry out lytic infection. 
B) One infects hyperthermophilic hosts while the other infects a hyperhalophilic host. 
C) One packages a dsDNA genome while the other packages a ssDNA genome. 
D) One appears to encode an obvious DNA polymerase while the other does not. 
E) One has a linear genome while the other has a circular genome. 
A) One can undergo lysogeny while the other can only carry out lytic infection. 
B) One infects hyperthermophilic hosts while the other infects a hyperhalophilic host. 
C) One packages a dsDNA genome while the other packages a ssDNA genome. 
D) One appears to encode an obvious DNA polymerase while the other does not. 
E) One has a linear genome while the other has a circular genome.

Question 15

Which of the following characteristics is common to many of the viruses that infect archaeal cells and distinguishes them from the phages that infect bacteria.

Accepted Answer

A) They release mature virions without lysing the host cell. 
B) Their viral genomes are very high in AT basepairs. 
C) Their viral genomes are linear. 
D) Their viral genomes are composed of double-stranded RNA. 
E) Their virions are composed of icosahedral capsids. 
A) They release mature virions without lysing the host cell. 
B) Their viral genomes are very high in AT basepairs. 
C) Their viral genomes are linear. 
D) Their viral genomes are composed of double-stranded RNA. 
E) Their virions are composed of icosahedral capsids.

Question 16

Some of the viruses that infect archaeal cells have linear dsDNA genomes with covalently closed ends.What is a major advantage of this feature?

Accepted Answer

A) It makes the genome more stable under low pH conditions. 
B) It allows the genome to be more easily packaged into the virion 
C) It allows the genome to be more easily integrated into the host cell genome. 
D) It allows the genome to use a self-priming mechanism for DNA replication. 
E) All of the above are correct. 
A) It makes the genome more stable under low pH conditions. 
B) It allows the genome to be more easily packaged into the virion 
C) It allows the genome to be more easily integrated into the host cell genome. 
D) It allows the genome to use a self-priming mechanism for DNA replication. 
E) All of the above are correct.

Question 17

Even though many of the viruses that infect archaeal cells do not kill their host,they often do which of the following?

Accepted Answer

A) Shut down host protein synthesis 
B) Increase the cell doubling time 
C) Decrease the cell doubling time 
D) Shut down genome replication 
E) Inhibit synthesis of host cell membranes 
A) Shut down host protein synthesis 
B) Increase the cell doubling time 
C) Decrease the cell doubling time 
D) Shut down genome replication 
E) Inhibit synthesis of host cell membranes

Question 18

Archaea are singled-celled microorganisms that share which of the following characteristics with eukaryotic cells?

Accepted Answer

A) Initiate translation of proteins with a methionine,not N-formyl-methionine. 
B) Contain histone-like proteins to condense their genomic DNA. 
C) Use a TATA-binding protein to initiate transcription of their genes. 
D) Have similar enzymes involved in DNA replication . 
E) All of the above are correct. 
A) Initiate translation of proteins with a methionine,not N-formyl-methionine. 
B) Contain histone-like proteins to condense their genomic DNA. 
C) Use a TATA-binding protein to initiate transcription of their genes. 
D) Have similar enzymes involved in DNA replication . 
E) All of the above are correct.

Question 19

Which of the following is a description of an IS element?

Accepted Answer

A) A short transposable DNA sequence 
B) A region of DNA where transcription begins 
C) A telomeric-like sequence at the ends of the DNA 
D) A region of the host chromosome where the viral DNA integrates 
E) A region of DNA that acts as an origin or replication 
A) A short transposable DNA sequence 
B) A region of DNA where transcription begins 
C) A telomeric-like sequence at the ends of the DNA 
D) A region of the host chromosome where the viral DNA integrates 
E) A region of DNA that acts as an origin or replication

Question 20

Some of the viruses that infect host cells in the euryarchaeota phyla have similar virion structures as the head-tail viruses in the Myoviridae and Siphoviridae families.

Accepted Answer

A) True 
 B)False

Exam 9: Viruses of Archaea

Viruses that infect archaeal cells have been isolated from all of the following environments EXCEPT:

In comparing the genomes of the viruses that infect archaeal cells,very few of the viral genomes have genes encoding an identifiable DNA polymerase.Give two possibilities that explain this observation.

Which of the following terms specifically describes archaeal organisms that can grow above 80oC?

Infection of the archaeal cell Acidianus with the virus ATV at the suboptimal temperature of 75oC leads to a productive lytic infection rather than lysogeny.

What is unusual about the virion of the Acidianus two-tailed virus?

The extrusion of the tails on the Acidianus two-tailed virus requires which of the following?

Which of the following can be found at the ends of the genome of a virus that infects archaeal cells?

Into which of the following genes in the host cell genome does the archaea virus SSV-1 integrate its genome?

Rudiviruses,a family of archaea viruses,are different from most other archaea viruses in that they lyse the host cell to release mature virions.

Many of the viruses that infect archaeal cells primarily carry out a lysogenic infection.Even if they do enter a productive infectious cycle,they can release new virions without killing the host cell.What might be the evolutionary advantages of these lifestyle features?

Archaea cells contain a nucleus like eukaryotic cells.

Viruses that infect archaeal cells have been observed to have all of the following virion shapes EXCEPT:

What information was used to identify the three domains of life?

Even though the two archaeal viruses HHPV-1 and HRPV-1 are clearly related to each other,based on genome and virion structures,they have one major difference.Which of the following describes this difference?

Which of the following characteristics is common to many of the viruses that infect archaeal cells and distinguishes them from the phages that infect bacteria.

Some of the viruses that infect archaeal cells have linear dsDNA genomes with covalently closed ends.What is a major advantage of this feature?

Even though many of the viruses that infect archaeal cells do not kill their host,they often do which of the following?

Archaea are singled-celled microorganisms that share which of the following characteristics with eukaryotic cells?

Which of the following is a description of an IS element?

Some of the viruses that infect host cells in the euryarchaeota phyla have similar virion structures as the head-tail viruses in the Myoviridae and Siphoviridae families.

Introduction to Virology 2

Virus Structure and Assembly

Virus Classification: the World of Viruses

Virus Entry

Single-Stranded Rna Bacteriophages

Microviruses

Bacteriophage

Bacteriophage Lambda

Cucumber Mosaic Virus

Picornaviruses

Flaviviruses

Togaviruses

Coronaviruses

Paramyxoviruses and Rhabdoviruses

Filovirouses

Bunyaviruses

Influenza Viruses

Reoviruses

Parvoviruses

Polyomaviruses

Papillomaviruses

Adenoviruses

Herpesviruses

Baculoviruses

Poxviruses

Viruses of Algae and Mimivirus

Retroviruses

Human Immunodeficiency Virus

Hepadnaviruses

Viroids and Hepatitis Delta Virus

Prions

Intrinsic Cellular Defenses Against Virus Infection

Innate and Adaptive Immune Responses to Virus Infection

Antiviral Vaccines

Antiviral Chemotherapy

Eukaryotic Virus Vectors

Filters

Which of the following terms specifically describes archaeal organisms that can grow above 80^oC?

Infection of the archaeal cell Acidianus with the virus ATV at the suboptimal temperature of 75^oC leads to a productive lytic infection rather than lysogeny.