Question 1

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase δ?

Accepted Answer

A)  DNA polymerase α
B)  DNA polymerase δ
C)  DNA polymerase β
D)  both DNA polymerase α and DNA polymerase β
E)  RNase H1F) All of the above
G) A) and D)

Question 2

Patients with the classical form of xeroderma pigmentosum have a defect in one of the genes involved in ______________.

Accepted Answer

A)  nucleotide excision repair
B)  replication
C)  base excision repair
D)  transcription
E)  base excitation repairF) A) and C)
G) C) and E)

Question 3

Who was the first to suggest semiconservative replication?

Accepted Answer

A)  Meselson and Stahl
B)  Hershey and Chase
C)  Watson and Crick
D)  Avery, McCarty and MacLeod
E)  Darwin and WallaceF) A) and D)
G) B) and D)

Question 4

What supplies the energy that drives the relief of mechanical strain by DNA gyrase?

Accepted Answer

A)  condensation of ATP
B)  condensation of GTP
C)  hydrolysis of ATP
D)  hydrolysis of GTP
E)  a proton gradientF) A) and B)
G) A) and C)

Question 5

Which type of DNA repair removes, via a cut-and-patch mechanism, a variety of bulky lesions, like pyrimidine dimers and nucleotides to which various chemical groups have been attached?

Accepted Answer

A)  nucleotide excision repair
B)  base excision repair
C)  mismatch repair
D)  double-strand breakage repair
E)  All of these are correct.F) B) and E)
G) A) and D)

Question 6

Why is an intact, linear double helix an ineffective template for DNA polymerase?

Accepted Answer

A)  It has a 3'-hydroxyl terminus, but lacks a template.
B)  It lacks a 3'-hydroxyl group, but has a template.
C)  It lacks a 3'-hydroxyl group and a template.
D)  It has a 3'-hydroxyl group and has a template.
E)  It lacks a 5'-hydroxyl group and has a template.F) A) and D)
G) B) and E)

Question 7

What is the advantage of transcription-coupled repair?

Accepted Answer

A)  It prevents cells from investing energy in transcription.
B)  It ensures that the genes of least importance to the cell receive the highest priority on the repair list.
C)  It ensures that the genes of greatest importance to the cell receive the highest priority on the repair list.
D)  It is repairs noncoding sequences preferentially.
E)  It is the most accurate method of repair.F) C) and E)
G) B) and E)

Question 8

What is the probability that, in E. coli, an incorrect nucleotide will be incorporated into DNA during replication and remain there?

Accepted Answer

A)  one in one billion nucleotides
B)  one in 1000 nucleotides
C)  one in four million nucleotides
D)  one in 100,000 to 1,000,000 nucleotides
E)  one in 10,000 nucleotidesF) A) and D)
G) A) and E)

Question 9

Bacteria are grown in a medium containing [15N]H4Cl for a number of generations so that all of the DNA is made of fully 'heavy' DNA. The bacteria are moved to a new medium and grown in [14N]H4Cl so that all subsequent new DNA will be 'light.' If replication were dispersive, what would the DNA look like after two generation times?

Accepted Answer

A)  All of the DNA is made of two 'light' strands.
B)  Half of the DNA is made of two 'light' strands and half of the DNA is made of one 'light' strand and one 'heavy' strand.
C)  All of the DNA is made of one 'heavy' strand and one 'light' strand.
D)  Each strand is made of a mixture of 'heavy' and 'light' DNA, with each strand being between 75% and 100% 'light.'
E)  Three quarters of the DNA is made of two 'light' strands and one quarter is made of two 'heavy' strands.F) A) and B)
G) A) and C)

Question 10

Which eukaryotic DNA polymerase is thought to be the primary DNA-synthesizing enzyme during replication of the lagging strand?

Accepted Answer

A)  polymerase α
B)  polymerase β
C)  polymerase ɤ
D)  polymerase δ
E)  polymerase εF) All of the above
G) A) and D)

Question 11

What is responsible for joining eukaryotic Okazaki fragments together?

Accepted Answer

A)  DNA ligase
B)  DNA polymerase α
C)  DNA polymerase δ
D)  DNA polymerase β
E)  RNase H1F) C) and D)
G) B) and E)

Question 12

Which of the following is an advantage of using RNA primers during initiation of a strand in replication?

Accepted Answer

A)  Using primers may decrease mistakes; such errors as mismatched bases are more likely during initiation than elongation, and the use of a short, removable RNA segment avoids inclusion of mismatched bases.
B)  Using primers slows down the process of replication, which increases accuracy of complementary base pairing.
C)  The RNA of the primers is more stable.
D)  The RNA of the primers is more likely to lead to changes in base sequence, which enhances the rate of mutation and thus evolution.
E)  The RNA of the primers allows more efficient packing of the chromosomes after its removal.F) B) and C)
G) A) and B)

Question 13

What is the mechanism of action of the anti-HIV drug AZT?

Accepted Answer

A)  it causes double-strand DNA breaks
B)  it inhibits DNA synthesis by reverse transcriptase
C)  it prevents transcription in infected cells
D)  it blocks the active site of DNA ligase
E)  it prevents viral entry into cellsF) B) and C)
G) B) and D)

Question 14

_________ are DNA unwinding enzymes that unwind the DNA in a reaction using the energy from ________ to move along one of the DNA strands, breaking the _______ holding the two strands together.

Accepted Answer

A)  DNA helicases, ATP dehydration, disulfide linkages
B)  DNA gyrases, ATP hydrolysis, hydrogen bonds
C)  DNA helicases, ATP hydrolysis, 3'-5'-phosphodiester linkages
D)  DNA helicases, ATP hydrolysis, hydrogen bonds
E)  DNA gyrases, ATP dehydration, hydrogen bondsF) D) and E)
G) A) and B)

Question 15

How can the replication of both DNA strands by two tethered polymerases be accomplished when the template strands run in opposite directions?

Accepted Answer

A)  One of the enzymes polymerizes DNA in the 3'->5' direction.
B)  The DNA of the lagging strand loops back on itself so it has same orientation as the leading strand template.
C)  The DNA of the leading strand loops back on itself so it has same orientation as the lagging strand template.
D)  The lagging strand is broken and then rejoined regularly to allow simultaneous synthesis.E) A) and B)
F) B) and C)

Question 16

The DNA polymerases is a relatively large family of polymerases in which each member is specialized for incorporating nucleotides opposite particular types of DNA lesions in the template strand engage in a type of DNA synthesis called __________. They have an unusually spacious active site that ____________.

Accepted Answer

A)  translesion synthesis; unwinds DNA double helices
B)  translesion synthesis; is able to physically accommodate altered nucleotides that would not fit in the active site of a replicative polymerase
C)  transdimensional synthesis; incorporates the nucleotide that would have paired with the undamaged version of the template base
D)  transdimensional synthesis; unwinds DNA synthesis
E)  transliteral synthesis; is able to physically accommodate altered nucleotides that would not fit in the active site of a replicative polymeraseF) A) and D)
G) C) and E)

Question 17

What binds to the ORC to assemble the prereplication complex (pre-RC) that is competent to initiate replication?

Accepted Answer

A)  the ORC factors
B)  MCM proteins
C)  competence factors
D)  initiation factors
E)  enlisting factorsF) All of the above
G) A) and C)

Question 18

Why did Kornberg initially think that the exonuclease activity he found in his DNA polymerase preparations was a contaminating enzyme?

Accepted Answer

A)  The action of exonucleases is a lot like endonuclease.
B)  The action of exonucleases is so dramatically opposed to the activity of DNA polymerases, to synthesize DNA.
C)  The action of exonucleases is exactly like the action of DNA polymerase.
D)  Purification was so difficult.
E)  Enzymes can often run the reverse reactions.F) B) and D)
G) B) and E)

Question 19

What is the name of the noncatalytic component of the DNA polymerase III holoenzyme that keeps the polymerase associated with the DNA template?

Accepted Answer

A)  β-pleated sheet
B)  α-helix
C)  β-clamp
D)  α-clamp
E)  β-clamF) A) and B)
G) None of the above

Question 20

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU) , which replaces thymidine in DNA. After two rounds of replication, what does the DNA look like?

Accepted Answer

A)  All chromatids have one strand that contains BrdU and one strand that does not.
B)  All chromatids have two strands that contain BrdU.
C)  Half of the chromatids have two strands that contain BrdU and half have two strands lacking BrdU.
D)  Both strands of each chromatid contain mixtures of BrdU and thymidine.
E)  Half of the chromatids have two strands that contain BrdU and half have one strand lacking BrdU and one strand containing BrdU.F) C) and D)
G) A) and C)

Exam 13: Dna Replication and Repair

Which type of DNA repair removes, via a cut-and-patch mechanism, a variety of bulky lesions, like pyrimidine dimers and nucleotides to which various chemical groups have been attached?

Correct Answer
verified

What is the advantage of transcription-coupled repair?

Correct Answer
verified

What is responsible for joining eukaryotic Okazaki fragments together?

Correct Answer
verified

Who was the first to suggest semiconservative replication?

Correct Answer
verified

What binds to the ORC to assemble the prereplication complex (pre-RC) that is competent to initiate replication?

Correct Answer
verified

Which of the following is an advantage of using RNA primers during initiation of a strand in replication?

Correct Answer
verified

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase δ?

Correct Answer
verified

What is the name of the noncatalytic component of the DNA polymerase III holoenzyme that keeps the polymerase associated with the DNA template?

Correct Answer
verified

___ are DNA unwinding enzymes that unwind the DNA in a reaction using the energy from to move along one of the DNA strands, breaking the _ holding the two strands together.

Correct Answer
verified

Which eukaryotic DNA polymerase is thought to be the primary DNA-synthesizing enzyme during replication of the lagging strand?

Correct Answer
verified

What is the mechanism of action of the anti-HIV drug AZT?

Correct Answer
verified

Why is an intact, linear double helix an ineffective template for DNA polymerase?

Correct Answer
verified

How can the replication of both DNA strands by two tethered polymerases be accomplished when the template strands run in opposite directions?

Correct Answer
verified

What is the probability that, in E. coli, an incorrect nucleotide will be incorporated into DNA during replication and remain there?

Correct Answer
verified

What supplies the energy that drives the relief of mechanical strain by DNA gyrase?

Correct Answer
verified

Patients with the classical form of xeroderma pigmentosum have a defect in one of the genes involved in ______________.

Correct Answer
verified

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU) , which replaces thymidine in DNA. After two rounds of replication, what does the DNA look like?

Correct Answer
verified

Why did Kornberg initially think that the exonuclease activity he found in his DNA polymerase preparations was a contaminating enzyme?

Correct Answer
verified

The DNA polymerases is a relatively large family of polymerases in which each member is specialized for incorporating nucleotides opposite particular types of DNA lesions in the template strand engage in a type of DNA synthesis called . They have an unusually spacious active site that __.

Correct Answer
verified

Correct Answer
verified

Exam 13: Dna Replication and Repair

Which type of DNA repair removes, via a cut-and-patch mechanism, a variety of bulky lesions, like pyrimidine dimers and nucleotides to which various chemical groups have been attached?

Correct AnswerverifiedShow Answer

What is the advantage of transcription-coupled repair?

Correct AnswerverifiedShow Answer

What is responsible for joining eukaryotic Okazaki fragments together?

Correct AnswerverifiedShow Answer

Who was the first to suggest semiconservative replication?

Correct AnswerverifiedShow Answer

What binds to the ORC to assemble the prereplication complex (pre-RC) that is competent to initiate replication?

Correct AnswerverifiedShow Answer

Which of the following is an advantage of using RNA primers during initiation of a strand in replication?

Correct AnswerverifiedShow Answer

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase δ?

Correct AnswerverifiedShow Answer

What is the name of the noncatalytic component of the DNA polymerase III holoenzyme that keeps the polymerase associated with the DNA template?

Correct AnswerverifiedShow Answer

_________ are DNA unwinding enzymes that unwind the DNA in a reaction using the energy from ________ to move along one of the DNA strands, breaking the _______ holding the two strands together.

Correct AnswerverifiedShow Answer

Which eukaryotic DNA polymerase is thought to be the primary DNA-synthesizing enzyme during replication of the lagging strand?

Correct AnswerverifiedShow Answer

What is the mechanism of action of the anti-HIV drug AZT?

Correct AnswerverifiedShow Answer

Why is an intact, linear double helix an ineffective template for DNA polymerase?

Correct AnswerverifiedShow Answer

How can the replication of both DNA strands by two tethered polymerases be accomplished when the template strands run in opposite directions?

Correct AnswerverifiedShow Answer

What is the probability that, in E. coli, an incorrect nucleotide will be incorporated into DNA during replication and remain there?

Correct AnswerverifiedShow Answer

What supplies the energy that drives the relief of mechanical strain by DNA gyrase?

Correct AnswerverifiedShow Answer

Patients with the classical form of xeroderma pigmentosum have a defect in one of the genes involved in ______________.

Correct AnswerverifiedShow Answer

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU) , which replaces thymidine in DNA. After two rounds of replication, what does the DNA look like?

Correct AnswerverifiedShow Answer

Why did Kornberg initially think that the exonuclease activity he found in his DNA polymerase preparations was a contaminating enzyme?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

___ are DNA unwinding enzymes that unwind the DNA in a reaction using the energy from to move along one of the DNA strands, breaking the _ holding the two strands together.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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