Question 1

The genome of the bacteriophage T7 has circularly permuted ends.

Accepted Answer

A) True 
 B)False

Question 2

One of the first proteins produced during the infection cycle of bacteriophage T7 inhibits the cellular enzymes EcoB and EcoK.Why is this important for the phage?

Accepted Answer

A)  This prevents transcription of the cellular genes.
B)  This allows transcription of the viral genes.
C)  This prevents the viral proteins from being degraded.
D)  This prevents the viral genome from being degraded.
E)  This shuts down host cell genome replication.

Question 3

What is the size and composition of the T7 bacteriophage genome?

Accepted Answer

A)  4000 nt of ssDNA
B)  4000 nt of ssRNA
C)  5,000 bp of dsDNA
D)  40,000 bp of dsDNA
E)  200,000 bp of dsDNA

Question 4

What is interesting about the promoters that direct transcription of the Class II and Class III genes from bacteriophage T7?

Accepted Answer

A)  They are very rich in GC basepairs.
B)  They are much longer and more complex than the host gene promoters.
C)  They can only be recognized by the viral RNA polymerase.
D)  They can be recognized by either the host or viral RNA polymerase.
E)  They are not very highly conserved. C

Question 5

The removal of the RNA primer leaves a gap in the newly synthesized viral genomic DNA.How does the bacteriophage T7 solve this problem?

Accepted Answer

A)  It produces concatemers of the viral genome.
B)  It circularizes the viral genome.
C)  It uses a special DNA polymerase to fill in the gaps.
D)  It leaves the RNA as part of the packaged viral genome.
E)  It uses a protein as a primer instead of RNA. A

Question 6

What would be observed in a cell infected with a T7 phage mutated in gene 3 (endonuclease gene) .

Accepted Answer

A)  No Class II mRNAs.
B)  No Class III mRNAs.
C)  Incomplete entry of the viral genome.
D)  Concatamers of the viral genome.
E)  Incomplete virus capsids. D

Question 7

What is the function of cleavage of the mRNAs from bacteriophage T7 by the host ribonuclease III?

Accepted Answer

A)  It processes the transcript into smaller more stable mRNAs.
B)  It produces a sequence that is recognized by the host cell ribosomes.
C)  It degrades the viral mRNAs after they have been translated into proteins.
D)  It removes introns from the viral mRNAs and produces a mature mRNA.
E)  It produces RNA primers required for viral DNA replication.

Question 8

The entry of the genome of the bacteriophage T7 is dependent on which of the following processes?

Accepted Answer

A)  Division of the infected host cell.
B)  Replication of the viral genome by host DNA polymerase.
C)  Translation of the viral genome by the host ribosomes.
D)  Transcription of viral genes by the viral RNA polymerase.
E)  Transcription of viral genes by the host RNA polymerase.

Question 9

What is the role of the viral RNA polymerase in the replication of the bacteriophage T7 genome?

Accepted Answer

A)  It binds to the single-stranded DNA and prevents reannealing.
B)  It helps to unwind the two strands of the viral genome.
C)  It produces the RNA primer on the leading strand.
D)  It produces the RNA primer on the lagging strand.
E)  It can switch from RNA synthesis to DNA synthesis.

Question 10

The promoters of the Class II and Class III genes in the bacteriophage T7 have the same -10 and -35 sequences as the promoters for host cell genes.

Accepted Answer

A) True 
 B)False

Question 11

The bacteriophage T7 produces a protein with an array of acidic amino acids that acts as a DNA mimic.Which of the following describes the function of this protein?

Accepted Answer

A)  It competitively inhibits the host restriction endonucleases.
B)  It binds to the viral genome and helps to package it into the head.
C)  It acts as a primer for DNA replication.
D)  It assists the entry of the viral genome into the host cell.
E)  It binds to the host cell RNA polymerase and directs it to transcribe viral genes.

Question 12

Describe how the RNA polymerase from bacteriophage T7,along with specific DNA sequences taken from the late T7 genes,can be used to produce high levels of a foreign protein in a bacterial cell.

Accepted Answer

The T7 RNA polymerase specifically recog...

Question 13

What is unique about the RNA polymerase encoded by the bacteriophage T7?

Accepted Answer

A)  It depends on host cell proteins for its function.
B)  It is composed of a single polypeptide.
C)  It is composed of many polypeptides.
D)  It can transcribe host genes in addition to viral genes.
E)  It can only transcribe the Class I genes on the T7 genome.

Question 14

Bacteriophage T7 was isolated from what source?

Accepted Answer

A)  Unprocessed waste from a sewage treatment plant
B)  Commercially available treatment for intestinal infections
C)  Soil found on a farm
D)  Water samples taken from a polluted river
E)  Animal manure.

Question 15

Which of the following enzymes is NOT involved in replication of the bacteriophage T7 genome?

Accepted Answer

A)  Single-Strand DNA binding protein
B)  Lysozyme
C)  DNA ligase
D)  RNA polymease
E)  RNA primase/helicase

Question 16

Which part of the T7 virion binds to the lipopolysaccharide molecules on the outer cell membrane of the host cell?

Accepted Answer

A)  The vertices of the icosahedral head.
B)  The tail fibers.
C)  The portal protein.
D)  The regions of three-fold symmetry on the icosahedral head.
E)  The envelope glycoprotein.

Question 17

How are the genes in the genome of the bacteriophage T7 arranged in the genome?

Accepted Answer

A)  By when they are expressed during the viral replication cycle.
B)  By their function during the viral replication cycle.
C)  By the amount of GC bases they contain.
D)  By their size,shortest to longest.
E)  Both a and b are correct.

Question 18

Holin is a small membrane-specific protein produced by the bacteriophge T7.Which of the following describes the function of this protein?

Accepted Answer

A)  It ensures the replication of the entire T7 genome.
B)  It helps the T7 phage particles lyse the host cell.
C)  It creates the portal in the phage head where the viral genome is packaged.
D)  It degrades the host cell wall during entry of the viral genome.
E)  It cleaves the viral genome during packaging.

Question 19

Incubation of bacterial cells infected with the phage T7 with an inhibitor of protein synthesis will allow only the Class I mRNAs to be produced.

Accepted Answer

A) True 
 B)False

Question 20

What genetic technique helped scientists in the 1970s to map the genes in the genome of bacteriophage T7?

Accepted Answer

A)  Restriction enzyme mapping
B)  DNA sequencing
C)  Conditional-lethal mutants
D)  Southern blotting
E)  Site-directed mutagenesis

Exam 7: Bacteriophage

The genome of the bacteriophage T7 has circularly permuted ends.

Correct AnswerverifiedShow Answer

One of the first proteins produced during the infection cycle of bacteriophage T7 inhibits the cellular enzymes EcoB and EcoK.Why is this important for the phage?

Correct AnswerverifiedShow Answer

What is the size and composition of the T7 bacteriophage genome?

Correct AnswerverifiedShow Answer

What is interesting about the promoters that direct transcription of the Class II and Class III genes from bacteriophage T7?

Correct AnswerverifiedC

The removal of the RNA primer leaves a gap in the newly synthesized viral genomic DNA.How does the bacteriophage T7 solve this problem?

Correct AnswerverifiedA

What would be observed in a cell infected with a T7 phage mutated in gene 3 (endonuclease gene) .

Correct AnswerverifiedD

What is the function of cleavage of the mRNAs from bacteriophage T7 by the host ribonuclease III?

Correct AnswerverifiedShow Answer

The entry of the genome of the bacteriophage T7 is dependent on which of the following processes?

Correct AnswerverifiedShow Answer

What is the role of the viral RNA polymerase in the replication of the bacteriophage T7 genome?

Correct AnswerverifiedShow Answer

The promoters of the Class II and Class III genes in the bacteriophage T7 have the same -10 and -35 sequences as the promoters for host cell genes.

Correct AnswerverifiedShow Answer

The bacteriophage T7 produces a protein with an array of acidic amino acids that acts as a DNA mimic.Which of the following describes the function of this protein?

Correct AnswerverifiedShow Answer

Describe how the RNA polymerase from bacteriophage T7,along with specific DNA sequences taken from the late T7 genes,can be used to produce high levels of a foreign protein in a bacterial cell.

Correct AnswerverifiedThe T7 RNA polymerase specifically recog...View AnswerShow Answer

What is unique about the RNA polymerase encoded by the bacteriophage T7?

Correct AnswerverifiedShow Answer

Bacteriophage T7 was isolated from what source?

Correct AnswerverifiedShow Answer

Which of the following enzymes is NOT involved in replication of the bacteriophage T7 genome?

Correct AnswerverifiedShow Answer

Which part of the T7 virion binds to the lipopolysaccharide molecules on the outer cell membrane of the host cell?

Correct AnswerverifiedShow Answer

How are the genes in the genome of the bacteriophage T7 arranged in the genome?

Correct AnswerverifiedShow Answer

Holin is a small membrane-specific protein produced by the bacteriophge T7.Which of the following describes the function of this protein?

Correct AnswerverifiedShow Answer

Incubation of bacterial cells infected with the phage T7 with an inhibitor of protein synthesis will allow only the Class I mRNAs to be produced.

Correct AnswerverifiedShow Answer

What genetic technique helped scientists in the 1970s to map the genes in the genome of bacteriophage T7?

Correct AnswerverifiedShow Answer

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The T7 RNA polymerase specifically recog...
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