Question 1

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

Accepted Answer

C

Question 2

Which of the following best describes the mechanism of DNA replication in which both parental strands remain together following replication?
A)Dispersive
B)Semi-conservative
C)Conservative
D)All of the answers are correct

Accepted Answer

In conservative DNA replication, both parental strands remain together and only the daughter strands are formed after replication. The other options, dispersive and semi-conservative, involve some degree of separation and mixing of parental and daughter strands. Therefore, the correct answer is (C) Conservative.

Question 3

Bacterial DNA has how many origins of replication?
A)0
B)1
C)10
D)Depends on the size of the DNA

Accepted Answer

Bacterial DNA has one origin of replication, also known as oriC. This single origin initiates the duplication of the entire bacterial chromosome.

Question 4

You have discovered a strain of
A)$\alpha$
B)$\beta$
C)$\varepsilon$
D)$\sigma$
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?

Accepted Answer

The answer of You have discovered a strain of
A)$\alpha$
B)$\beta$
C)$\varepsilon$
D)$\sigma$
E)coli that...

Question 5

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

Accepted Answer

DNA ligase is responsible for joining and sealing the nicks between adjacent Okazaki fragments on the lagging strand, therefore forming a continuous DNA strand.

Question 6

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

Accepted Answer

Okazaki fragments are short, discontinuous lengths of DNA synthesized on the lagging strand during replication. They are synthesized in the opposite direction to the movement of the replication fork, so the fragments must be synthesized in a series of shorter pieces that are subsequently ligated together. These fragments assist in the synthesis of DNA from the lagging strand.

Question 7

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

Accepted Answer

All of the answers are correct. The double-helix of DNA has directionality, with one end having a 5' carbon and the other end having a 3' carbon. The two strands are arranged in an anti-parallel arrangement, meaning that one strand runs in the 5' to 3' direction while the other strand runs in the 3' to 5' direction. Additionally, the two strands are complementary, with base pairing between A and T and between G and C.

Question 8

DNA polymerases add new nucleotides in what direction?
A)5' to 3'
B)3 ' to 5'
C)Both directions

Accepted Answer

DNA polymerases add new nucleotides in the 5' to 3' direction, which means that the nucleotide is attached to the 3' end of the growing strand while the polymerase moves along in the 5' to 3' direction.

Question 9

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

Accepted Answer

The purpose of DNA replication is to produce two identical daughter strands from the original parental strands. The daughter strands serve as templates for future DNA replication and ensure that genetic information is passed on accurately during cell division. Therefore, choice A is the correct answer. The other options (B, C, D) are incorrect as they do not accurately reflect the purpose of DNA replication.

Question 10

How many DNA polymerases are found in prokaryotes?
A)5
B)7
C)9
D)12

Accepted Answer

Prokaryotes have five DNA polymerases, which are named Polymerase I, II, III, IV, and V. Each of these polymerases has a distinct set of roles in DNA replication, repair, and recombination. For example, Polymerase III is responsible for the bulk of DNA synthesis during replication, while Polymerase II is involved in DNA repair.

Question 11

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

Accepted Answer

DNA helicase enzymes move in the 5' to 3' direction along the DNA during DNA replication, splitting the double-stranded DNA into two separate strands. This movement is necessary to allow the replication machinery to access the template strand and synthesize a new complementary strand in the 5' to 3' direction.

Question 12

Which of the following best describes the mechanism of DNA replication in which both a parental strand and daughter strand are combined following replication?
A)Dispersive
B)Semi-conservative
C)Conservative
D)All of the answers are correct

Accepted Answer

Semi-conservative replication is the mechanism by which DNA replicates, where each parent strand serves as a template for the formation of a new daughter strand. The resulting DNA molecule consists of one parental strand and one newly synthesized daughter strand. Dispersive replication involves the random distribution of parental and daughter segments within the newly synthesized DNA strands, while conservative replication involves the complete separation of parental and daughter DNA strands.

Question 13

Responsible for the majority of DNA replication.
A)DNA ligase
B)DNA primase
C)Topoisomerase
D)DNA polymerase I
E)DNA polymerase III

Accepted Answer

DNA polymerase III is responsible for the majority of DNA replication in prokaryotes. It is the main polymerase enzyme involved in adding nucleotides to the growing DNA chain.

Question 14

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

Accepted Answer

DNA polymerase III requires an RNA primer to begin synthesis of the new daughter strands, as it can only add nucleotides to an existing strand.

Question 15

Manufactures a 10-12 base segment of RNA.
A)DNA ligase
B)Primase
C)Topoisomerase
D)DNA polymerase I
E)DNA polymerase III

Accepted Answer

Primase is the enzyme responsible for synthesizing short RNA primers during DNA replication. These primers are required by DNA polymerases to initiate DNA synthesis. Since the option only mentions synthesis of RNA, primase is the most appropriate choice.

Question 16

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

Accepted Answer

The first generation of replication in the Meselson and Stahl experiment disproved the conservative theory of replication, which suggested that the original double-stranded DNA molecule remains intact and serves as a template for the synthesis of a completely new double-stranded DNA molecule, while the newly synthesized double-stranded DNA molecule is composed entirely of new nucleotides. In the experiment, however, the intermediate band observed for the first generation of replication was consistent with a semiconservative model, where each daughter DNA molecule contains one parental strand and one newly synthesized strand. The dispersive model, which suggests that both strands of the original double-stranded DNA molecule are broken down and then mixed to form two new double-stranded DNA molecules with interspersed parental and newly synthesized nucleotides, was also disproved in later generations of replication in the experiment.

Question 17

Synthesizes the lagging strand of the DNA.
A)DNA ligase
B)DNA primase
C)Topoisomerase
D)DNA polymerase I
E)DNA polymerase III

Accepted Answer

DNA polymerase III is the enzyme that synthesizes the lagging strand of the DNA. This enzyme has the ability to add nucleotides in a 5' to 3' direction and can also proofread its work, correcting any mistakes in base pairing.

Question 18

Which of the following is not correct concerning the initiation of bacterial replication?
A)It involves a region of the DNA called oriC
B)DNA 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

Accepted Answer

The strands are initially separated at AT-rich regions of DNA, not GC-rich regions.

Question 19

Prevents supercoiling ahead of the replication fork.
A) DNA ligase
B) DNA primase
C) Topoisomerase
D) DNA polymerase I
E) DNA polymerase III

Accepted Answer

Topoisomerases are responsible for preventing supercoiling ahead of the replication fork by breaking and rejoining the DNA strands, allowing them to rotate and relieve tension. DNA ligase joins Okazaki fragments, DNA primase synthesizes RNA primers, DNA polymerase I is involved in the removal of RNA primers and the filling of gaps, and DNA polymerase III is responsible for the majority of DNA synthesis during replication.

Question 20

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

Accepted Answer

DNA polymerase I is responsible for removing the RNA primers and filling in the gaps with DNA nucleotides, sealing the newly synthesized fragments together.

Quiz 11: DNA Replication

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?

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

Bacterial DNA has how many origins of replication?

You have discovered a strain of

Attaches adjacent Okazaki fragments, forming a continuous DNA strand.

Okazaki fragments do which of the following?

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

DNA polymerases add new nucleotides in what direction?

The purpose of DNA replication is to produce ______.

How many DNA polymerases are found in prokaryotes?

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

Which of the following best describes the mechanism of DNA replication in which both a parental strand and daughter strand are combined following replication?

Responsible for the majority of DNA replication.

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

Manufactures a 10-12 base segment of RNA.

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

Synthesizes the lagging strand of the DNA.

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

Prevents supercoiling ahead of the replication fork.

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