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

What is the main function of DNA polymerase III in E. coli?

Accepted Answer

Synthesis of new DNA strands by adding nucleotides in the 5' to 3' direction

Question 4

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

Accepted Answer

5' to 3' on both the leading and lagging strands

Question 5

What is the role of DNA ligase during DNA replication?

Accepted Answer

Joins Okazaki fragments by forming phosphodiester bonds

Question 6

Which of the following equations represents the chemical reaction catalyzed by DNA polymerase during DNA synthesis?

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 proofreading activity and induced fit for correct nucleotides

Question 8

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

Accepted Answer

To allow the entire genome to be replicated in a reasonable amount of time

Question 9

Which enzyme is responsible for removing RNA primers and replacing them with DNA in E. coli?

Accepted Answer

DNA polymerase I

Question 10

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

Accepted Answer

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

Question 11

Which of the following best describes the function of telomerase?

Accepted Answer

It adds repetitive DNA sequences to the 3' overhang of linear chromosomes

Question 12

A mutation in the DnaA box of E. coli would most likely affect which stage of DNA replication?

Accepted Answer

Initiation

Question 13

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized discontinuously on the lagging strand

Question 14

Which of the following is NOT a function of DNA polymerase I in E. coli?

Accepted Answer

Joining Okazaki fragments

Question 15

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

Accepted Answer

They retain telomerase activity, which maintains telomere length

Question 16

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

Accepted Answer

$$dNTP \rightarrow dNMP + PP_i$$

Question 17

Which of the following is a unique feature of eukaryotic DNA replication compared to prokaryotic DNA replication?

Accepted Answer

Multiple origins of replication per chromosome

Question 18

What is the function of the 3' to 5' exonuclease activity of DNA polymerase?

Accepted Answer

To remove mismatched nucleotides during proofreading

Question 19

Which of the following best describes the role of the sliding clamp (β subunit) in DNA replication?

Accepted Answer

It increases the processivity of DNA polymerase by keeping it attached to the DNA

Question 20

A patient is found to have a mutation that inactivates telomerase in their stem cells. What is the most likely long-term consequence for their cells?

Accepted Answer

Progressive shortening of chromosome ends with each cell division

DNA Replication: Mechanisms, Models, and Telomere Maintenance

Study Guide - Practice Questions