Question 1

Which phase of the eukaryotic cell cycle is responsible for the doubling of nuclear DNA content?

Accepted Answer

S phase

Question 2

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

Accepted Answer

Semiconservative replication

Question 3

During DNA replication, which enzyme is responsible for unwinding the DNA double helix using energy from ATP hydrolysis?

Accepted Answer

DNA helicase

Question 4

What is the primary function of single-stranded binding proteins (SSB) during DNA replication?

Accepted Answer

To stabilize unwound DNA strands and prevent them from reannealing

Question 5

In E. coli, which sequence is AT-rich and serves as the origin of replication?

Accepted Answer

oriC

Question 6

Which enzyme synthesizes short RNA primers required for DNA polymerase to initiate DNA synthesis?

Accepted Answer

Primase

Question 7

Why is DNA replication described as 'semiconservative'?

Accepted Answer

Each new DNA molecule contains one parental strand and one newly synthesized strand

Question 8

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 9

What is the direction of DNA synthesis by DNA polymerases?

Accepted Answer

$$5' \rightarrow 3'$$

Question 10

Which of the following best describes the role of topoisomerase during DNA replication?

Accepted Answer

It relieves supercoiling ahead of the replication fork

Question 11

A mutation in the gene encoding DNA polymerase III in E. coli would most likely affect which process?

Accepted Answer

Synthesis of the leading and lagging DNA strands

Question 12

What experimental evidence did Meselson and Stahl use to distinguish old and newly synthesized DNA strands?

Accepted Answer

Equilibrium density centrifugation using $$^{15}N$$ and $$^{14}N$$

Question 13

Which of the following statements about Okazaki fragments is TRUE?

Accepted Answer

They are short DNA segments synthesized on the lagging strand

Question 14

What is the function of telomerase in eukaryotic cells?

Accepted Answer

It adds repetitive DNA sequences to the ends of chromosomes

Question 15

Which of the following is a consequence of the end-replication problem in linear chromosomes?

Accepted Answer

Loss of nucleotides from chromosome ends with each round of replication

Question 16

During DNA replication, which activity allows DNA polymerase to correct errors?

Accepted Answer

3' to 5' exonuclease activity

Question 17

In eukaryotic DNA replication, what is the role of the origin recognition complex (ORC)?

Accepted Answer

It binds to the replication origin and recruits other proteins for initiation

Question 18

Which of the following best explains why telomerase activity is important in cancer cells?

Accepted Answer

It prevents chromosome ends from being degraded, allowing unlimited cell division

Question 19

Which of the following statements about DNA polymerase is FALSE?

Accepted Answer

It can initiate DNA synthesis without a primer

Question 20

A patient with Werner syndrome lacks a functional WRN protein. What cellular process is most directly affected?

Accepted Answer

Telomere capping and protection

DNA Replication, Repair, and Recombination (Chapter 17) – Becker's World of the Cell

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