Deck 25: DNA Replication, repair and Recombination

Question 1

Matching
Choose the correct answer from the list.Not all the answers will be used.

DNA separated at the replication fork is stabilized by ______ .

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Answer 1

SSB

Question 2

Matching
Choose the correct answer from the list.Not all the answers will be used.

Direct reversal of pyrimidine dimers in prokaryotic cells is catalyzed by a DNA _____.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Answer 2

photolyase

Question 3

Matching
Choose the correct answer from the list.Not all the answers will be used.

Enzymes that undergo many rounds of polymerization catalysis before dissociating from the substrate are described as highly ______.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Answer 3

processive

Question 4

When a section of DNA is damaged and polymerization cannot proceed,_____ repair can reconstitute the damaged replication fork.

A)mismatch
B)nucleotide excision
C)recombination
D)photoreactivation
E)base excision

Question 5

Positive correlations between mutagenesis and carcinogenesis

A)are increased with teleomere capping.
B)are reverted via nick translation.
C)are examined using the Ames test.
D)increase with photoreactivation.
E)None of the above is correct .

Question 6

Pol I synthesizes new DNA with very high fidelity,due to its

A)high processivity.
B)3' $\to$ 5'exonuclease activity.
C)helicase association with the primase.
D)5' $\to$ 3' exonuclease activity.
E)all of the above.

Question 7

Matching
Choose the correct answer from the list.Not all the answers will be used.

E.coli primer synthesis is catalyzed by a ______.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 8

Matching
Choose the correct answer from the list.Not all the answers will be used.

The RNA segment to which DNA residues are added during replication is the ______.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 9

Matching
Choose the correct answer from the list.Not all the answers will be used.


-The process whereby nucleotides are removed from the 5' end of one DNA segment while nucleotides are added to the 3' end of the immediately preceding DNA segment is called ______.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 10

Which of the following would result in single stranded DNA?

A)Klenow fragment
B)Klentaq I
C)DnaB
D)DnaG
E)pol III

Question 11

Matching
Choose the correct answer from the list.Not all the answers will be used.

G-rich polynucleotides can form _______

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 12

Pol I is proteolytically cleaved to yield the ____,which lacks 5' $\to$ 3' exonuclease activity.

A)Klenow fragment
B)Klentaq1 polymerase
C)Okazaki fragment
D)ligase
E)primase

Question 13

Free radical damage to DNA often results in
(I)pyrimidine dimers
(II)point mutations
(III)insertions
(IV)base excision

A)I only.
B)II only.
C)I,II.
D)II,III.
E)I,IV.

Question 14

The presence of proflavin is likely to induce

A)pyrimidine dimers.
B)point mutations.
C)deletions.
D)transversions.
E)Any of the above may occur.

Question 15

Capping is important because

A)it likely protects the telomere ends from becoming shortened.
B)it likely prevents DNA repair mechanisms from initiating at the telomeres.
C)it likely results in increased processivity on the eukaryotic chromosome.
D)all of the above
E)none of the above

Question 16

Matching
Choose the correct answer from the list.Not all the answers will be used.

Genes can be moved by _______.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 17

Matching
Choose the correct answer from the list.Not all the answers will be used.

In yeast,DNA replication begins at sequences known as ______.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 18

Matching
Choose the correct answer from the list.Not all the answers will be used.

Termination of replication fork movement in E.coli involves the binding of the ______ protein at a Ter site.

A) SSB
B) Tus
C) primosome
D) ARS
E) ATS
F) primer
G) transposons
H) nick translation
I) photolyase
J) processive
K) G-loops
L) G-quartets
M) accurate
N) lagging strand synthesis
O) MCM
P) abortive

Question 19

E.coli leading and lagging strand synthesis takes place at the

A)the Klenow fragment binding site.
B)Pol III & Tus interface.
C)multiprotein replisome.
D)origin recognition complex.
E)telomere.

Question 20

Replication of circular DNA occurs at the "bubbles" or "eyes",also called ______ .

A)" $\theta$ structures"
B)" $\phi$ bubbles"
C)" $\theta$ bubbles"
D)" $\sigma$ structures"
E)" $\sigma$ bubbles"

Question 21

Which of the following statements about Pol I is FALSE?

A)Experiments demonstrate that Pol I exhibits exonuclease activity.
B)Pol I is not the primary replicase in E.coli.
C)Mutation analysis demonstrates that Pol I functions in DNA repair.
D)Mutation analysis demonstrates the Pol I activity is not essential for cell viability.
E)Experiments have successfully utilized Pol I to radioactively label DNA in lab experiments.

Question 22

DNA ligase can be activated by which of the following?
(I)The coupled hydrolysis of NAD⁺ to (NMN⁺)+ AMP.
(II)The coupled hydrolysis of ATP to AMP + PP_i.
(III)The coupled hydrolysis of GTP to GMP + PP_i.

A)I only
B)II only
C)III only
D)I,II
E)I,III

Question 23

Which of the following statement(s)about DNA polymerase III (Pol III)is (are)TRUE?
(I)DNA polymerase III has greater accuracy than RNA polymerase.
(II)Pol III is the primary replicase of E.coli.
(III)Pol III does not contain 5' to 3' exonuclease activity.

A)I,II.
B)II,III.
C)III only.
D)I only.
E)I,II,III.

Question 24

Deamination of cytosine leads to the formation of

A)thymine.
B)5-methylcytosine.
C)uracil.
D)5-bromouracil.
E)5-methyluracil.

Question 25

Which of the following statements about the fidelity of replication is FALSE?

A)Cells maintaining an equal concentration of each dNTP helps maintain fidelity.
B)DNA polymerase catalyzes synthesis in a two-stage reaction,ensuring the proper base is added.
C)Cells viability is removed when DNA point mutations are incorporated.
D)Pol I and Pol III are both involved in increasing fidelity.
E)Specific repair systems repair and maintain DNA.

Question 26

Lagging stands are polymerized in the ______ direction,and the DNA fragments are about ______ nucleotides (nt)long in eukaryotic cells.

A)5' to 3',100-200
B)5' to 3',1000-2000
C)3' to 5',100-400
D)3' to 5',1000-50000
E)none of the above

Question 27

Which of the following activities does E.coli DNA polymerase III contain?
(I)5'→3' polymerase
(II)5'→3' exonuclease
(III)3'→5' exonuclease

A)I only
B)I,II
C)II only
D)I,III
E)I,II,III

Question 28

Defects in the proteins ______,which associate with RAD-51,are correlated with several types of cancer.

A)BRCA1 and BRCA2
B)RecU and RecB
C)Pol $\alpha$ and Pol $\beta$
D)DSB and NHEJ
E)RecA and RecUGA

Question 29

The experiments of Reiji Okazaki allowed determination that DNA synthesis occurs in
(I)a continuous fashion.
(II)different ways on the lagging strand than the leading strand.
(III)resulted in new synthesized DNA fragments containing the radioactive isotope.

A)I,II,III
B)II,III
C)I,II
D)I,III
E)II only

Question 30

Suppose Meselson & Stahl had observed the following data in their famous experiment involving a switch from medium containing 15N to 14N.What would they have concluded about the nature of DNA replication?

A)They still would have concluded that DNA replication is semiconservative.
B)They would have concluded that DNA replication is conservative.
C)They would have concluded that DNA replication is dispersive/random.
D)None of the above is correct.
E)Cannot be determined with the information given.

Question 31

Synthesis of telomeres requires the enzyme ______,which is a type of ______.

A)telomerase,helicase
B)telomerase,ribonucleoprotein
C)ribonuclease,riboprotein
D)ribotelase,ligase
E)none of the above

Question 32

Which of the following statements about DNA methylation is TRUE?
(I)Methylation plays a role in genomic imprinting.
(II)Methylation can influence gene regulation.
(III)Methylation plays a role in restriction modification systems.
(IV)Methylation occurs in prokaryotic cells,but not eukaryotic cells.

A)I,II,III,IV
B)I,II,III
C)II,III
D)II,III,IV
E)II only

Question 33

Which of the following enzymes catalyze the creation of AP sites for base excision repair?

A)exonuclease
B)endonuclease
C)ligase
D)glycosylase
E)methylase

Question 34

What kind of mutation has occurred?

A)transition
B)transversion
C)insertion
D)deletion
E)none of the above

Question 35

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

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 work at one replication fork,while the DNA pol I works at the other.This way they don't meet exactly at the other side of the chromosome.
D)The DNA pol IIIs do most of the work.DNA pol I only has to work on the telomers.
E)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.

Question 36

Which of the following statements about telomerase is FALSE?
(I)Telomerase is an RNA polymerase.
(II)Telomerase has a 5'->3' polymerase activity.
(III)Telomerase uses RNA as a template.
(IV)The product of the telomerase-catalyzed reaction is rich in G and T.

A)I only
B)II only
C)II,III
D)I,III
E)II,IV

Question 37

What enzymes would be used to repair this error?

A)methyl-directed mismatch repair enzymes
B)nucleotide excision repair enzymes
C)methyl-directed double strand break repair enzymes
D)UvrABC plus UvrD
E)None of the above systems can repair this error

Question 38

In most organisms,replication proceeds in a ______ manner from the ______.

A)discontinuous;leading strand
B)unidirectional;chromosome ends
C)bidirectional;replication origin
D)bidirectional;chromosome ends
E)discontinuous;chromosome ends

Question 39

Which of the following are TRUE about transposons?
(I)They are normal components of plasmids.
(II)They often carry genes for antibiotic resistance.
(III)They insert at a target sequence that is a repetitive unit of about 200 bp.

A)I,II,III
B)I,II
C)II,III
D)II only
E)III only

Question 40

E.coli DNA repair enzymes act on the sequence.Which of the following will result?

A)The underlined A will be changed to a C.
B)The underlined G will be changed to a T.
C)The underlined A will be methylated.
D)The underlined G will be methylated.
E)More than one of the above is correct

Question 41

Considering the following eukaryotic DNA polymerases,which of the following has the highest fidelity?

A)DNA pol $\alpha$
B)DNA pol $\beta$
C)DNA pol $\delta$
D)All have high fidelity
E)All have low fidelity

Question 42

The DNA sequence shown below is copied by the Klenow fragment.Which of the following would most likely result?
5' TGCGTGCACTCGA 3'

A)identical
B)5' TGCGT 3'
C)5' TGCAGTGACGCT 3'
D)cannot predict
E)none of the above

Question 43

Bacteria have obtained the $\beta$ -lactamase gene which encodes a protein that renders all $\beta$ -lactem antibodies such as ampicillin and penicillin inactive.Which of the following would result in an increased number of bacteria with this ability?
(I)a transposon with the $\beta$ -lactamase gene
(II)a recombination event within the original strain that results in a point mutation inactivating $\beta$ -lactamase
(III)an insertion in the original strain rendering transposase inactive
(IV)a deletion in the insertion sequence of the transposon

A)I,II,III,IV
B)I only
C)II only
D)II,III
E)III,IV

Question 44

A new DNA polymerase exhibits: (1)high processivity, (2)low fidelity,and (3)ability to replace RNA with DNA.Which of the following is probably TRUE?

A)It has 3' exonuclease activity.
B)It has 5'exonuclease activity.
C)It has RNA primase activity.
D)It is not associated with a clamp.
E)both A and B

Question 45

Which of the following describes the usefulness of primase?

A)It removes RNA bases and replaces them with DNA bases.
B)It seals nicks.
C)It adds an RNA starter sequence which can be elongated.
D)It is only required on the leading strand.
E)It unwinds the DNA.

Question 46

Which of the following would result in increased processivity in E.coli?

A)β (sliding)clamp
B)primosome
C)helicase
D)Dna B
E)Dna G

Question 47

Which of the following describes the Holliday junction?

A)point where DNA base excision repair initiates
B)crossover point involving 4-stranded DNA structure in homologous recombination
C)insertion point of a gene flanked in transposons
D)point where MutS binds to initiate SOS response
E)none of the above

Question 48

Which of the following can be extended by DNA polymerase?

A)a single strand of DNA ending in a nucleotide with a free 3' OH
B)a RNA single strand with a ribonucleotide with a free 3' OH
C)a single strand DNA end in a deoxyribonucleotide with free 5' P
D)a RNA single strand
E)all of the above

Question 49

Use the following diagram to complete the sentences below

" ______ is the enzyme which catalyzes phosphodiester bond formation on both strands.Processivity of DNA pol is increased when associated with ____.DNA untwisting is accomplished by ______."

A)A,C,B
B)A,B,C
C)B,C,A
D)A,D,B
E)A,E,B

Question 50

In molecular biology labs researchers often use E.coli strains that are RecA minus (recA⁻)when transforming a cloned gene into a plasmid which explains why
(I)a Rec A-strain would have fewer replication errors.
(II)a Rec A-strain would have less opportunity forming DNA mutations.
(III)a Rec A-strain would increase error repair.

A)I only.
B)II only.
C)III only.
D)I,II
E)II,III