Deck 11: Dna Replication

Question 1

Attaches adjacent Okazaki fragments, forming a continuous DNA strand.

A) DNA ligase
B) DNA primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Answer 1

A

Question 2

Which of the following is not correct concerning the initiation of bacterial replication?

A) It involves a region of the DNA called oriC
B) DnaA proteins bind to the DNA to begin separation of the strands
C) The strands are initially separated at GC-rich regions of DNA
D) Following initial separation, DNA helicase enzymes continue to unwrap the DNA

Answer 2

C

Question 3

Which of the following best describes the mechanism of DNA replication in which both parental strands remain together following replication?

A) Dispersive
B) Semiconservative
C) Conservative
D) All of the answers are correct

Answer 3

C

Question 4

Which of the following best describes the double-helix of DNA?

A) It has directionality
B) The strands are arranged in an anti-parallel arrangement
C) The strands are complementary
D) All of the answers are correct

Question 5

You have discovered a strain of E. coli that grows very slowly-the generation time is nearly 12 hours compared to the normal 20-30 minutes. Upon further investigation, you find a mutation in the DNA polymerase III gene. What subunit of the holoenzyme does this mutation affect the most?

A) α
B) β
C) ε
D) δ

Question 6

You have isolated what appears to be alien DNA. While studying its replication, you performed the exact experiment Meselson and Stahl did. After three generations, the DNA is subjected to a CsCl gradient and only one band appears. What type of replication does this DNA undergo?

A) Semiconservative
B) Conservative
C) Dispersive

Question 7

Synthesizes the lagging strand of the DNA.

A) DNA ligase
B) DNA primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Question 8

Responsible for the majority of DNA replication.

A) DNA ligase
B) DNA primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Question 9

DNA polymerase III has the ability to begin synthesis of the new daughter strands immediately following the formation of the replication fork.

Question 10

How many DNA polymerases are found in prokaryotes?

A) 5
B) 7
C) 9
D) 12

Question 11

Manufactures a 10-12 base segment of RNA.

A) DNA ligase
B) Primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Question 12

What is the name for the mechanism of DNA replication in which one parental strand and one daughter strand are combined following replication?

A) Dispersive
B) Semiconservative
C) Conservative
D) All of the answers are correct

Question 13

Okazaki fragments do which of the following?

A) Assist in forming the replication fork
B) Bind to the oriC region
C) Assist in the synthesis of DNA from the lagging strand
D) Reform the double-helix following replication
E) None of the answers are correct

Question 14

The purpose of DNA replication is to produce ________.

A) Two daughter strands
B) Two parental strands
C) Two template strands
D) None of the answers are correct

Question 15

DNA helicase enzymes move in what direction along the DNA during DNA replication?

A) 5' to 3'
B) 3' to 5'
C) They remain stationary

Question 16

The first round of replication in the Meselson and Stahl experiment disproved which theory of replication?

A) Semiconservative
B) Conservative
C) Dispersive
D) None-it took more than one round to disprove the theory

Question 17

DNA polymerases add new nucleotides in what direction?

A) 5' to 3'
B) 3 ' to 5'
C) Both directions

Question 18

Fills in small regions of DNA where the RNA primers were located.

A) DNA ligase
B) DNA primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Question 19

Bacterial DNA has how many origins of replication per chromosome?

A) 0
B) 1
C) 10
D) Depends on the size of the DNA

Question 20

Removes supercoiling ahead of the replication fork.

A) DNA ligase
B) DNA primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Question 21

Which of the following is an example of a processive enzyme?

A) DNA polymerase I
B) DNA polymerase III
C) DNA ligase
D) Okazaki fragments

Question 22

The origin of replication in bacteria is called OriC.

Question 23

The proofreading of newly synthesized DNA by DNA Pol III occurs in the ________.

A) 5' to 3' direction
B) 3' to 5' direction
C) Both directions

Question 24

DNA polymerase III has an error in replication once every 100 million nucleotides.

Question 25

The movement of the replication fork in bacterial replication is unidirectional.

Question 26

After the action of the helicase, single-stranded binding proteins keep the parental DNA strands from reforming a double-helix.

Question 27

What functions are accomplished by the primosome?

A) Tracking along DNA
B) Tracking along DNA, separating double stranded DNA
C) Tracking along DNA, separating double stranded DNA, synthesizing RNA primers
D) Tracking along DNA, separating double stranded DNA, synthesizing RNA primers, adding nucleotides

Question 28

In eukaryotes, which of the following is similar to the oriC region of prokaryotes?

A) Dam
B) ARS elements
C) Promoters
D) Telomeres

Question 29

The Meselson-Stahl experiments used 35S radioisotopes to determine the mechanism of DNA replication.

Question 30

Which of the following stops the replication of DNA in prokaryotes?

A) Tus proteins
B) DNA ligase
C) Okazaki fragments
D) The end of the chromosome

Question 31

The synthesis of the daughter strand of DNA occurs away from the replication fork in the leading strand.

Question 32

You extract DNA from an E. coli cell and observe it is hemimethylated (only methylated on one strand). Which strand of DNA is older?

A) The methylated strand
B) The strand that is not methylated
C) Neither-they are the same "age."

Question 33

Which of the following is NOT a reason for the high fidelity of DNA synthesis of DNA Pol III?

A) The hydrogen bonding between purines and pyrimidines is stable.
B) The DNA polymerase is unlikely to form bonds between nucleotides if they are mismatched.
C) The DNA polymerase has exonuclease functions.
D) The DNA polymerase has the ability to change the structure of the base in order to form the correct bond.

Question 34

DNA polymerase is a primer-dependent enzyme that functions only in the 5'-3' direction. These are the two most fundamental concepts to understanding this enzyme. Based on this, which of the following enzyme pairs are analogous in prokaryotes and eukaryotes?

A) DNA pol I : DNA pol α
B) DNA pol II : DNA pol β
C) DNA pol III : DNA pol δ
D) All of the answers are correct

Question 35

Translesion-replicating polymerases are ________.

A) only active in skin cells
B) used to replicate damaged DNA
C) used to induce genetic diversity
D) None of the answers are correct

Question 36

What types of mutants were essential to the discovery of new replication enzymes?

A) Gain-of-function mutations
B) Lethal mutations
C) Temperature-sensitive mutations
D) None of the answers are correct

Question 37

Which of the following is a restriction placed on DNA polymerase?

A) DNA polymerase can attach new nucleotides only in the 5' to 3' direction.
B) DNA polymerases must begin synthesis using an RNA primer.
C) DNA polymerases must have a template strand to copy from.
D) All of the above are restrictions of DNA polymerase.

Question 38

The Meselson-Stahl experiments supported the model of dispersive DNA replication.

Question 39

DNA polymerases are unable to replicate what areas of the chromosome?

A) Centromeres
B) 3' end of telomeres
C) Origins of replication

Question 40

Replication usually begins in GC rich regions due to the presence of only 2 hydrogen bonds between the bases.

Question 41

If eukaryotic cells evolved such that lagging strand DNA synthesis could occur continuously (without the use of Okazaki fragments), what enzyme would likely no longer be needed for DNA replication?

A) Flap endonuclease
B) Helicase
C) Primase
D) Topoisomerase

Question 42

Catenanes can only form in cells with circular chromosomes, such as bacteria.

Question 43

You are performing a biochemical purification of enzymes involved in DNA replication. You have purified the replisome. You wish to purify the primosome. You perform further separation techniques on your purified replisome. How will you test to determine that you have purified the primosome?

A) You should confirm that your sample has helicase and primase activity, but not the ability to synthesize DNA.
B) You should confirm that your sample has the ability to synthesize DNA and has primase activity, but no helicase activity.
C) You should confirm that your sample has helicase and primase activity. This is the only test that is needed.
D) You should confirm that your sample has primase activity and can synthesize DNA. This is the only test that is needed.

Question 44

The problem in synthesizing the 3' end of chromosomes is solved by the use of the telomerase enzyme.

Question 45

DNA polymerase III synthesizes DNA at the rate of 300 nucleotides per minute.

Question 46

The ability of the DNA polymerase to remove mismatched bases is called exonuclease cleavage (proofreading).

Question 47

A primosome consists of a polymerase and a single-stranded binding protein.

Question 48

You are in the lab trying to synthesize DNA in vitro. You are upset because the lab seems to be out of dNTPs (deoxynucleoside triphosphates) but you find a tube of dNMPs (deoxynucleoside monophosphates) in the freezer. You add this to your replication reaction instead of dNTPs. Will your reaction work? Why or why not?

A) No, cleavage of dNTP drives the formation of the covalent bond between the nucleoside monophosphate and the growing DNA strand.
B) Yes, only the nucleoside monophosphate ultimately is incorporated into the growing DNA strand.
C) No, all three phosphates on the nucleoside triphosphate are incorporated into the growing DNA strand.
D) Yes, the formation of the covalent bond between the nucleoside monophosphate and the growing DNA strand is energetically favorable.