Question 1

Which model of DNA replication was supported by the results of the Meselson-Stahl experiment after two generations in 14N medium?

Accepted Answer

Semiconservative model

Question 2

During DNA replication, which enzyme is responsible for synthesizing the RNA primer required for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 3

In E. coli, which DNA polymerase is primarily responsible for the removal of RNA primers and replacement with DNA on the lagging strand?

Accepted Answer

DNA polymerase I

Question 4

What is the function of the DnaA protein during the initiation of bacterial DNA replication?

Accepted Answer

It binds to DnaA box sequences at the origin to initiate DNA unwinding.

Question 5

Which of the following best describes the directionality of DNA synthesis by DNA polymerases?

Accepted Answer

5' to 3' direction only

Question 6

Which of the following equations correctly represents the chemical reaction catalyzed by DNA polymerase during nucleotide addition?

Accepted Answer

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

Question 7

Why is DNA replication considered to have high fidelity?

Accepted Answer

DNA polymerase has a 3' to 5' exonuclease proofreading activity.

Question 8

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized discontinuously on the lagging strand.

Question 9

In eukaryotic DNA replication, what is the primary reason for the presence of multiple origins of replication on each chromosome?

Accepted Answer

To allow the large linear chromosomes to be replicated in a reasonable amount of time.

Question 10

What is the 'end replication problem' in eukaryotic cells?

Accepted Answer

DNA polymerase cannot fully replicate the 5' ends of linear chromosomes, leading to progressive shortening.

Question 11

Which enzyme is responsible for extending the 3' overhang at the ends of eukaryotic chromosomes?

Accepted Answer

Telomerase

Question 12

Which of the following best describes the composition of telomerase?

Accepted Answer

It contains both protein and an RNA component that serves as a template.

Question 13

A mutation in the gene encoding the sliding clamp (β subunit) of DNA polymerase III in E. coli would most likely result in which of the following?

Accepted Answer

Decreased processivity of DNA polymerase III

Question 14

Which of the following is a function of DNA ligase during DNA replication?

Accepted Answer

Joining Okazaki fragments by forming phosphodiester bonds

Question 15

Which of the following best explains why cancer cells can divide indefinitely?

Accepted Answer

They retain telomerase activity, maintaining telomere length.

Question 16

Which of the following sequences is a typical telomeric repeat in humans?

Accepted Answer

$$TTAGGG$$

Question 17

During DNA replication, which of the following events occurs at the replication fork?

Accepted Answer

Helicase separates the two parental DNA strands.

Question 18

Which of the following is a direct result of the bidirectional nature of DNA replication in E. coli?

Accepted Answer

Two replication forks are formed at the origin and move in opposite directions.

Question 19

A patient is found to have a mutation in the gene encoding DNA polymerase δ in their cells. Which process would be most directly affected?

Accepted Answer

Replication of the lagging strand during S phase

Question 20

Which of the following best describes the role of the 3' to 5' exonuclease activity of DNA polymerase?

Accepted Answer

It proofreads newly synthesized DNA and removes mismatched nucleotides.

DNA Replication: Mechanisms, Models, and Telomere Maintenance

Study Guide - Practice Questions