Question 1

Which of the following statements best describes the semiconservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental strand and one newly synthesized strand.

Question 2

The Meselson-Stahl experiment provided evidence for which model of DNA replication?

Accepted Answer

Semiconservative

Question 3

During DNA replication in E. coli, which enzyme is responsible for unwinding the DNA double helix at the replication fork?

Accepted Answer

Helicase (DnaB)

Question 4

What is the primary function of the sliding clamp during DNA replication?

Accepted Answer

To anchor DNA polymerase to the template strand, increasing processivity

Question 5

Which of the following best explains why multiple origins of replication are necessary in eukaryotic chromosomes?

Accepted Answer

Eukaryotic genomes are much larger and would take too long to replicate from a single origin.

Question 6

Which enzyme removes RNA primers and replaces them with DNA nucleotides in E. coli?

Accepted Answer

DNA polymerase I

Question 7

A mutation in the gene encoding the tau (	au) protein in E. coli would most likely affect which aspect of DNA replication?

Accepted Answer

Coordination of leading and lagging strand synthesis by tethering DNA polymerase III core enzymes

Question 8

Which of the following is a direct consequence of the inability of DNA polymerases to initiate synthesis de novo?

Accepted Answer

RNA primers must be synthesized by primase to provide a 3' OH group.

Question 9

In the context of DNA replication, what is the main role of topoisomerase?

Accepted Answer

To relieve torsional stress and prevent supercoiling ahead of the replication fork

Question 10

A patient with dyskeratosis congenita has a mutation in the DKC1 gene. Which cellular process is most directly affected?

Accepted Answer

Telomerase function and telomere maintenance

Question 11

Which of the following equations correctly represents the number of hydrogen bonds in a DNA segment with $$n_{AT} A-T $$pairs and $$n_{GC} G-C $$pairs?

Accepted Answer

$$2n_{AT} + 3n_{GC}$$

Question 12

Which of the following best describes the difference between leading and lagging strand synthesis?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments.

Question 13

Which protein in eukaryotes is functionally analogous to the sliding clamp in bacteria?

Accepted Answer

PCNA (proliferating cell nuclear antigen)

Question 14

A researcher observes that after several generations, a mouse line with a TERT gene knockout shows developmental defects. What is the most likely explanation?

Accepted Answer

Progressive shortening of telomeres leads to chromosome instability and apoptosis.

Question 15

Which of the following best explains why DNA polymerase has a lower error rate during replication?

Accepted Answer

It possesses a 3' to 5' exonuclease activity for proofreading.

Question 16

Which of the following is the correct sequence of events during lagging strand synthesis in E. coli?

Accepted Answer

Primase synthesizes RNA primer, DNA pol III extends Okazaki fragment, DNA pol I removes primer and fills gap, ligase seals nick

Question 17

Which of the following best describes the function of telomerase?

Accepted Answer

It extends the 3' end of the template strand using an RNA template to prevent chromosome shortening.

Question 18

If a bacterial cell has a mutation that prevents the function of single-stranded binding protein (SSB), what is the most likely consequence during DNA replication?

Accepted Answer

The separated DNA strands would reanneal, preventing replication.

Question 19

Which of the following equations correctly represents the number of phosphodiester bonds in a double-stranded DNA molecule with $$n$$ nucleotides?

Accepted Answer

$$2(n-2)$$

DNA Replication: Mechanisms, Enzymes, and Regulation

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