Deck 20: Dna Replication,damage and Repair

Question 1

_____________ refers to the fact that once DNA polymerase holoenzyme starts replicating DNA it remains bound to the DNA template and catalyzes the addition of several nucleotides to the growing strand.

Answer 1

Processivity

Question 2

The fact that rifampicin inhibits M13 phage replication helped support the fact that

A)antibiotics can be used to study DNA replication.
B)RNA polymerase is used to make primers for DNA synthesis.
C)DNA polymerase is necessary for DNA synthesis.
D)Helicases are necessary for DNA synthesis.
E)DNA ligase is necessary to connect Okazaki fragments.

Answer 2

B

Question 3

Which of the following is not a characteristic of prokaryotic single stranded DNA binding proteins?

A)They are not essential for cell replication.
B)They stimulate homologous DNA polymerase.
C)They aid helicase action.
D)They keep DNA strands from annealing.
E)They bind more tightly to ssDNA than to dsDNA.

Answer 3

A

Question 4

DNA polymerase synthesizes DNA in the ___ to ____ direction.'

Question 5

Which of the following statements is not true concerning DNA replication in prokaryotes?

A)DNA replication is semiconservative.
B)DNA replication is semidiscontinuous.
C)DNA replication is RNA dependent.
D)DNA replication requires only one enzyme.
E)There is one origin of replication.

Question 6

The _________ fragment of DNA Pol I is commonly used in vitro to perform DNA end-filling experiments.

Question 7

The DNA polymerase involved in error-free by-pass that inserts dAMPs across from pyrimidine dimers is

A)DNA Pol I.
B)DNA Pol II.
C)DNA Pol III.
D)DNA Pol $\eta$ .
E)DNA Pol https://storage.examlex.com/TB6246/.

Question 8

Which of the following repair mechanisms is a damage bypass mechanism,not an actual repair mechanism?

A)DNA photolyase
B)base excision repair
C)nonhomologous end joining
D)mismatch repair
E)recombination repair

Question 9

Which of the following agents causes DNA damage by forming pyrimidine dimers?

A)X-rays
B)gamma radiation
C)UV radiation
D)alkylating agents
E)ethidium bromide

Question 10

The discovery of _________ fragments helped prove the semidiscontinuous nature of DNA replication.

Question 11

Another term for the Nucleotide Excision Repair enzyme system is_____________.

Question 12

The __________ strand in DNA replication is synthesized discontinuously.

Question 13

E.coli Base Excision repair starts with the enzyme ___________ clipping out the damaged base and leaving an apurinic or apyrimidinic site.

Question 14

The process by which electrophiles,such as ethylmethane sulfonate,add carbon containing groups to DNA is called____________.

Question 15

Which of the following mammalian cell DNA polymerases is not correctly matched with its function?

A)DNA Pol $\alpha$ -priming DNA synthesis
B)DNA Pol $\beta$ -DNA repair
C)DNA Pol $\gamma$ -elongation of both strands
D)DNA Pol $\delta$ -ligation of DNA strands
E)DNA Pol $\varepsilon$ -DNA repair

Question 16

The most common type of DNA damage repair is

A)excision repair.
B)photoreactivation.
C)suicide enzyme repair.
D)DNA photolyase.
E)proofreading repair.

Question 17

The enzyme responsible for bacterial DNA replication is _________.

Question 18

In most organisms the direction of DNA replication is ______________.

Question 19

Enzymes that introduce transient single stranded or double stranded breaks in DNA are called______________.

Question 20

By _____________ the adenine found in the sequence GATC on the parental DNA strand,E.coli is able to differentiate the parental strand from the mismatched base pairs in the daughter strand.

Question 21

In transcription,coupled nucleotide excision repair RNA polymerase plays a role in detecting and melting damaged DNA.

Question 22

E.coli dnaB temperature sensitive mutants cannot undergo DNA replication at 40^oC due to the loss of helicase activity.

Question 23

E.coli DNA Polymerase III does not have perfect fidelity.This is a beneficial characteristic since mutations help the cell adapt to changing environments.

Question 24

$\lambda$ phage replicates its genome using unidirectional DNA replication.

Question 25

DNA photolyase in human cells is involved in breaking pyrimidine dimers formed by UV radiation.

Question 26

DNA under the control of one origin of replication is called a replicon.

Question 27

DNA damage is considered to be the same thing as a DNA mutation,such as a change from an A-T base pair to a G-C base pair.

Question 28

In E.coli,the antibiotic nalidixic acid prevents DNA replication by inhibiting DNA gyrase,which then causes positive supercoiling of the DNA.

Question 29

In error-free bypass,DNA polymerase $\eta$ inserts dAMPs across from pyrimidine dimers,thereby correcting all DNA damage caused by UV radiation.

Question 30

Chromatin remodeling is required for both homologous recombination and nonhomologous end-joining.

Question 31

Double stranded DNA breaks caused by ionizing radiation are the least dangerous type of DNA damage due to repair by homologous recombination.

Question 32

The $\varepsilon$ -subunit of DNA Polymerase III core enzyme functions in proofreading by having 5 $\rightarrow$ 3' exonuclease activity.

Question 33

In semiconservative replication of DNA the two parental strands stay together and the two new daughter strands are produced.