Deck 13: Dna Replication and Recombination

Question 1

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

Answer 1

False

Question 2

In the attachment of a nucleotide to a DNA strand,the cleavage of the dNTP into deoxyribonucleoside monophosphate and pyrophosphate is ________.

A) exergonic
B) endergonic
C) energy neutral

Answer 2

A

Question 3

Which enzyme 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 3

A

Question 4

The purpose of DNA replication is to produce ________.

A) two daughter strands
B) two parental strands
C) two template strands
D) four daughter strands

Question 5

How many origins of replication does a bacterial chromosome contain?

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

Question 6

The first generation 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 generation to disprove the theory.

Question 7

Which enzyme is responsible for the majority of DNA synthesis during replication?

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

Question 8

You are studying DNA replication in human cells. You discover a mutant cell line that can carry out DNA replication,but the final product contains both RNA and DNA fragments. What enzyme is likely to be missing in this cell line?

A) flap endonuclease
B) DNA ligase
C) DNA polymerase I
D) DNA helicase

Question 9

Which describes the mechanism of DNA replication in which the newly made double-stranded DNA contains one parental strand and one daughter strand?

A) dispersive
B) semiconservative
C) conservative

Question 10

How many DNA polymerases are found in prokaryotes?

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

Question 11

Select the statements that are true regarding the initiation of DNA replication in bacteria.

A) It involves a region of the DNA called oriC.
B) 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 separate the strands.

Question 12

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 a gene for one of the subunits of DNA polymerase III.What subunit is this mutation most likely to be in?

A) α
B) β
C) γ
D) δ

Question 13

DNA polymerases add new nucleotides in what direction?

A) 5′ to 3′
B) 3′ to 5′
C) both directions

Question 14

Which enzyme manufactures a 10-12 base segment of RNA?

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

Question 15

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 16

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

A) dispersive
B) semiconservative
C) conservative

Question 17

Which enzyme synthesizes the lagging strand of the DNA?

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

Question 18

Which enzyme 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

What enzyme relaxes supercoiling ahead of the replication fork?

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

Question 20

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

A) 5′ to 3′
B) 3′ to 5′
C) They travel in both directions.
D) They remain stationary.

Question 21

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

Question 22

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

Question 23

The rate at which DNA polymerase III synthesizes a new strand of DNA is 300 nucleotides per minute.

Question 24

What is the purpose of Okazaki fragments?

A) To assist in the formation of the replication fork
B) To allow DNA to be synthesized in the 5' to 3' direction on the leading strand
C) To allow DNA to be synthesized in the 5′ to 3′ direction on the lagging strand
D) To reform the double helix following replication

Question 25

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 26

The proofreading of the DNA occurs in the ________.

A) 5′ to 3′ direction
B) 3′ to 5′ direction
C) both directions

Question 27

Select the reasons that DNA synthesis occurs with a high degree of fidelity.

A) The hydrogen bonding between G and C or A and T is much more stable than between mismatched pairs.
B) The active site of DNA polymerase preferentially catalyzes the attachment of nucleotides when the correct bases are located in opposite strands.
C) DNA polymerase enzymatically removes mismatched nucleotides.
D) DNA polymerase has the ability to change the structure of the base in order to form the correct bond.

Question 28

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

Question 29

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

A) centromeres
B) 3′ ends
C) origins of replication
D) 5′ ends

Question 30

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

Question 31

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

Question 32

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

Question 33

DNA polymerase III carries out leading and lagging strand synthesis in prokaryotes. How many enzymes accomplish this task in eukaryotes (not counting primer creation)?

A) one
B) two
C) three
D) four

Question 34

The origin of replication in bacteria is called oriC.

Question 35

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 36

Based on their known functions,which of the enzymes in the following pairs play a similar role in prokaryotes and eukaryotes?

A) DNA pol I : DNA pol α
B) DNA pol II : DNA pol β
C) DNA pol III : DNA pol γ

Question 37

Select the limitations of the DNA polymerases used for DNA replication.

A) DNA polymerase can attach new nucleotides only in the 5′ to 3′ direction.
B) DNA polymerases must begin synthesis using a primer or existing DNA strand.
C) DNA polymerases must have a template strand to copy from.
D) DNA polymerases can attach new nucleotides in the 3′ to 5′ direction only on the lagging strand.

Question 38

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

A) centromeres
B) ARS elements
C) promoters
D) telomeres

Question 39

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

Question 40

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

Question 41

The problem of replicating the 3′ ends of chromosomes is solved by using the enzyme telomerase.

Question 42

Homologous recombination that leads to genetic diversity occurs during meiosis II.

Question 43

What process does the Holliday model help explain?

A) recombination between homologous chromosomes
B) recombination between sister chromatids
C) the creation of shortened chromosomes
D) replication initiation

Question 44

In E.coli,which protein(s)are necessary for the cell to recognize double-stranded breaks and conduct recombination during meiosis?

A) RecG
B) RecA
C) RecBCD
D) RuvABC

Question 45

Recombination between sister chromatids produces new combinations of alleles that may be beneficial to the species.

Question 46

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

Question 47

A heteroduplex is a region within a DNA double helix that contains base mismatches that can lead to gene conversion.

Question 48

Which of the following best describes the function of the RecA protein in E.coli?

A) Promotes strand invasion and D-loop formation in the double-stranded break model
B) Recognizes double-stranded breaks in the DNA
C) Involved in the initial formation of Holliday junctions
D) Resolves Holliday junctions into separate chromosomes

Question 49

Which of the following may account for the process of gene conversion?

A) DNA mismatch repair
B) DNA gap repair
C) DNA proofreading
D) Telomerase errors
E) Flap endonuclease

Question 50

Which recombination model involves formation of a D-loop?

A) double-stranded break model
B) Holliday model
C) single-stranded break model