Question 1

Which statement best describes the semiconservative model of DNA replication?

Accepted Answer

Each parental DNA strand serves as a template for a new complementary strand, resulting in daughter DNA molecules with one parental and one new strand.

Question 2

During DNA replication, which enzyme is responsible for relieving supercoiling ahead of the replication fork?

Accepted Answer

Topoisomerase (such as gyrase)

Question 3

What is the direction of synthesis for a new DNA strand during replication?

Accepted Answer

5' to 3'

Question 4

Which of the following is required for DNA polymerase to initiate synthesis of a new DNA strand?

Accepted Answer

A free 3'-OH group provided by an RNA primer

Question 5

In a bacterial cell, DNA replication begins at a specific location called oriC. What is the significance of this site?

Accepted Answer

It is the origin of replication where the pre-replication complex assembles and DNA synthesis is initiated.

Question 6

Which enzyme synthesizes the short RNA primer required for DNA polymerase to begin DNA synthesis?

Accepted Answer

Primase

Question 7

What is the role of single-strand binding proteins (SSB) during DNA replication?

Accepted Answer

They stabilize and protect single-stranded DNA at the replication fork.

Question 8

Which of the following best explains why DNA replication is considered bidirectional?

Accepted Answer

Replication proceeds in both directions away from the origin, forming two replication forks.

Question 9

A mutation in the gene encoding DNA ligase would most directly affect which process during DNA replication?

Accepted Answer

Joining of Okazaki fragments on the lagging strand

Question 10

Which of the following equations correctly represents the formation of a phosphodiester bond during DNA synthesis?

Accepted Answer

$$dNTP + (DNA)_{n} \rightarrow (DNA)_{n+1} + PP_i$$

Question 11

Which protein motif is commonly found in DNA-binding proteins that recognize specific DNA sequences during replication initiation?

Accepted Answer

Helix-turn-helix (HTH) motif

Question 12

In eukaryotic cells, why are multiple origins of replication necessary?

Accepted Answer

To allow rapid and complete replication of large linear chromosomes.

Question 13

Which enzyme is responsible for unwinding the DNA double helix at the replication fork?

Accepted Answer

Helicase

Question 14

A patient is treated with a drug that inhibits topoisomerase II. What is the most likely effect on DNA replication?

Accepted Answer

Supercoiling ahead of the replication fork will not be relieved, leading to DNA breakage and stalling of replication.

Question 15

Which of the following best describes the function of the replisome during DNA replication?

Accepted Answer

It is a large complex aggregate of proteins and enzymes that coordinate DNA synthesis at the replication fork.

Question 16

Which of the following is true regarding the synthesis of the lagging strand during DNA replication?

Accepted Answer

It is synthesized discontinuously as short fragments called Okazaki fragments.

Question 17

If a mutation prevents the formation of RNA primers during DNA replication, which process would be most directly affected?

Accepted Answer

Initiation of DNA synthesis by DNA polymerase

Question 18

Which of the following best explains why DNA polymerase cannot initiate DNA synthesis de novo?

Accepted Answer

It requires a free 3'-OH group to add nucleotides, which is provided by a primer.

Question 19

Which of the following enzymes is responsible for joining the ends of Okazaki fragments to form a continuous DNA strand?

Accepted Answer

DNA ligase

DNA Replication: Mechanisms, Enzymes, and Molecular Machinery

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