Question 1

Which of the activities of DNA Polymerase I is most important in its role of proofreading?

Accepted Answer

A)   Polymerase activity.
B)   Ability to nick intact double stranded DNA.
C)   5' → 3' exonuclease.
D)   3' → 5' exonuclease.
E)   None of these is used for proofreading.F) A) and D)
G) A) and C)

Question 2

Which of the following is NOT an observed event in the flow of genetic information?

Accepted Answer

A)   DNA --> RNA
B)   RNA --> DNA
C)   RNA --> RNA
D)   DNA --> DNA
E)   RNA --> ProteinF)  Protein --> RNAG)  All of the choices ARE observedH) A) and E)
I) B) and C)

Question 3

Which of the following activities does E. coli DNA polymerase III lack ?

Accepted Answer

A)   5' → 3' polymerase
B)   5' → 3' exonuclease
C)   3' → 5' exonuclease
D)   E. coli DNA polymerase III has ALL of the above activities.E) B) and C)
F) A) and D)

Question 4

When the synthesis of new DNA is directed by an original template DNA molecule

Accepted Answer

A)   the DNA produced has two newly formed strands (no change in the original DN
A)  
B)   two DNA molecules are formed, each with one new strand and one strand from the original DNA
C)   there is random arrangement of newly formed and original DNA on the two strands of the DNA produced
D)   no information is available on this subjectE) A) and D)
F) A) and B)

Question 5

Which of the following is not an activity of DNA Polymerase I?

Accepted Answer

A)   Polymerase activity.
B)   Ability to nick intact double stranded DNA.
C)   5' → 3' exonuclease.
D)   3' → 5' exonuclease.
E)   All of these are present in DNA Pol I.F) A) and E)
G) All of the above

Question 6

The mechanism for all template-directed synthesis of any type of nucleic acid involves the following:

Accepted Answer

A)   Nucleophilic attack of a 3' hydroxyl toward a nucleoside triphosphate, releasing PPi.
B)   Nucleophilic attack of a 5' hydroxyl toward a nucleoside triphosphate, releasing PPi.
C)   Nucleophilic attack of a 3' hydroxyl toward a nucleoside triphosphate, releasing Pi.
D)   Nucleophilic attack of a 5' hydroxyl toward a nucleoside triphosphate, releasing Pi.
E)   More than one of these would work, since the mechanism is not universal.F) A) and B)
G) A) and C)

Question 7

Semiconservative replication implies that

Accepted Answer

A)   each of the new double stranded DNA molecules contains one of the original intact strands and one completely new strand.
B)   one of the new double stranded DNA molecules contains both of the original strands, while the other contains two new strands.
C)   each of the new double stranded DNA molecules contains strands that are composed of segments of original and newly synthesized material.
D)   None of these.E) A) and B)
F) A) and C)

Question 8

Which of the following is not a function of DNA Polymerase III?

Accepted Answer

A)   Polymerization.
B)   Ligating the final products.
C)   Proofreading.
D)   Clamping on to the template.
E)   None of these are functions of DNA Polymerase IIIF) None of the above
G) B) and D)

Question 9

In Escherichia coli , the enzyme principally responsible for the synthesis of new DNA strands is

Accepted Answer

A)   DNA polymerase I
B)   DNA polymerase III
C)   DNA ligase
D)   primaseE) All of the above
F) None of the above

Question 10

A prokaryotic replisome typically contains three molecules of DNA pol III, but only one molecule of DNA pol I. Why?

Accepted Answer

A)   The DNA pol I works on the leading strand, while DNA pol IIIs work on the Okazaki fragments. since there are several of those, it takes more proteins to keep up.
B)   DNA pol I has a built-in proofreading exonuclease; DNA pol III does not. The second DNA pol III is needed to follow the first to accomplish the necessary proofreading.
C)   The DNA pol IIIs do most of the work. DNA pol I only has to work on the telomers.
D)   DNA pol I replaces the RNA primers with DNA, which really only needs to be done repetitively on one strand, while both strands are worked on by the DNA pol IIIs.E) B) and C)
F) A) and D)

Question 11

The primer for in vivo DNA replication is:

Accepted Answer

A)   The 3' hydroxyl of the preceding Okazaki fragment.
B)   A short piece of RNA.
C)   A nick made in the DNA template.
D)   A primer is not always required for DNA replication.
E)   All of these are true.F) All of the above
G) B) and C)

Question 12

In order to replicate both strands, E. coli

Accepted Answer

A)   displaces one of the strands and folds it back so both strands face in the same direction, so they can be synthesized at once.
B)   synthesizes each strand in the opposite direction (one 5' → 3', one 3' → 5') , so they can be synthesized at once.
C)   only synthesizes one strand at a time.D) A) and B)
E) A) and C)

Question 13

The DNA polymerases in eukaryotes have similar functions to those found in bacteria, but they are not identical.

Accepted Answer

A) True 
 B)False

Question 14

The mechanism of breakage and reunion of DNA strands during recombination was proposed by:

Accepted Answer

A)   Messelson and Stahl
B)   Messelson and Weigle
C)   Robin Holliday
D)   Francis CrickE) None of the above
F) A) and B)

Question 15

All the following describe the general mechanism of DNA synthesis, except :

Accepted Answer

A)   From the perspective of the DNA template strands, one strand is made 5' → 3' while the other strand is made 3' → 5'.
B)   The strands become separated during synthesis.
C)   Synthesis occurs in both directions from the starting site of synthesis.
D)   Synthesis of DNA is a very accurate process.
E)   All of these are correct.F) None of the above
G) A) and D)

Question 16

If replication were conservative instead of semi-conservative, the famous Meselson and Stahl experiment would have shown which of the following results after the first round of replication?

Accepted Answer

A)   All of the double helices would have been heavy chains
B)   All of the double helices would have been light chains
C)   Half of the double helices would have been all heavy chains and the other half would have been all light chains
D)   All of the double helices would have been a combination of a heavy strand and a light strandE) A) and C)
F) A) and B)

Question 17

Which of the following is not required for optimal DNA replication?

Accepted Answer

A)   Primase
B)   DNA Polymerase II.
C)   Single strand binding proteins.
D)   Gyrase
E)   All of these are necessary.F) D) and E)
G) None of the above

Question 18

Recombination:

Accepted Answer

A)   occurs randomly throughout a chromosome
B)   occurs more often in areas called hot spots
C)   is a process that only happens under controlled laboratory conditions
D)   is a spontaneous process that requires no enzymesE) A) and D)
F) A) and C)

Question 19

The following enzyme is responsible for the bulk of DNA synthesis during replication.

Accepted Answer

A)   DNA Polymerase I
B)   DNA Polymerase II
C)   DNA Polymerase III
D)   DNA Polymerases IV
E)   All four can make lots of DNA rapidly.F) A) and E)
G) C) and E)

Question 20

Semiconservative replication of DNA was established experimentally by

Accepted Answer

A)   gel electrophoresis.
B)   ultraviolet spectroscopy.
C)   column chromatography.
D)   density-gradient centrifugation.E) A) and D)
F) B) and C)

Exam 10: Biosynthesis of Nucleic Acids Replication

The primer for in vivo DNA replication is:

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In Escherichia coli , the enzyme principally responsible for the synthesis of new DNA strands is

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Semiconservative replication implies that

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A prokaryotic replisome typically contains three molecules of DNA pol III, but only one molecule of DNA pol I. Why?

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All the following describe the general mechanism of DNA synthesis, except :

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When the synthesis of new DNA is directed by an original template DNA molecule

Correct AnswerverifiedShow Answer

Which of the following is not a function of DNA Polymerase III?

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The following enzyme is responsible for the bulk of DNA synthesis during replication.

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If replication were conservative instead of semi-conservative, the famous Meselson and Stahl experiment would have shown which of the following results after the first round of replication?

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Which of the following is not an activity of DNA Polymerase I?

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In order to replicate both strands, E. coli

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Which of the following is NOT an observed event in the flow of genetic information?

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Semiconservative replication of DNA was established experimentally by

Correct AnswerverifiedShow Answer

Recombination:

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Which of the activities of DNA Polymerase I is most important in its role of proofreading?

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The mechanism of breakage and reunion of DNA strands during recombination was proposed by:

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Which of the following activities does E. coli DNA polymerase III lack ?

Correct AnswerverifiedShow Answer

The mechanism for all template-directed synthesis of any type of nucleic acid involves the following:

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The DNA polymerases in eukaryotes have similar functions to those found in bacteria, but they are not identical.

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Which of the following is not required for optimal DNA replication?

Correct AnswerverifiedShow Answer

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