Question 1

Which of the following best describes the antiparallel nature of DNA?

Accepted Answer

One DNA strand runs 5' to 3', while the other runs 3' to 5'.

Question 2

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

Accepted Answer

Helicase

Question 3

What is the primary function of DNA ligase during DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 4

Which of the following statements about the semi-conservative model of DNA replication is correct?

Accepted Answer

Each new DNA molecule consists of one parental and one new strand.

Question 5

A mutation in the gene encoding primase would most directly affect which step of DNA replication?

Accepted Answer

Synthesis of RNA primers required for DNA polymerase to begin replication

Question 6

Which enzyme removes RNA primers and replaces them with DNA nucleotides during DNA replication?

Accepted Answer

DNA polymerase I

Question 7

Why are Okazaki fragments formed during DNA replication?

Accepted Answer

Because DNA polymerase can only synthesize DNA in the 5' to 3' direction, and the lagging strand is oriented 3' to 5'

Question 8

Which of the following best describes the role of single-stranded binding proteins (SSBPs) during DNA replication?

Accepted Answer

They prevent re-annealing of separated DNA strands.

Question 9

A scientist observes that DNA replication in a cell is proceeding very slowly and the DNA is becoming supercoiled ahead of the replication fork. Which enzyme is most likely malfunctioning?

Accepted Answer

Topoisomerase

Question 10

Which of the following sequences correctly represents the order of events during DNA replication?

Accepted Answer

Helicase unwinds DNA → Primase synthesizes RNA primer → DNA polymerase III extends DNA → DNA polymerase I replaces RNA primer → Ligase joins fragments

Question 11

Which of the following best explains why DNA polymerase cannot initiate DNA synthesis on its own?

Accepted Answer

It requires a free 3' hydroxyl group provided by an RNA primer.

Question 12

A patient is found to have a mutation that prevents the formation of multiple origins of replication on their chromosomes. What is the most likely consequence?

Accepted Answer

DNA replication will be slower, especially in large eukaryotic chromosomes.

Question 13

Which of the following is a correct description of the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in short fragments.

Question 14

Which of the following best describes the chemical structure of a DNA nucleotide?

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 15

Which of the following is NOT a function of DNA polymerase III during DNA replication?

Accepted Answer

Replacing RNA primers with DNA nucleotides

Question 16

A researcher adds radioactive deoxyribonucleotide triphosphates (dNTPs) to a cell-free DNA replication system. Where would you expect to find the radioactivity after replication is complete?

Accepted Answer

In the newly synthesized DNA strands

Question 17

Which of the following best explains why the lagging strand requires multiple primers during DNA replication?

Accepted Answer

It is synthesized discontinuously in short fragments, each requiring a new primer.

Question 18

If a mutation prevented the function of sliding clamp proteins during DNA replication, what would be the most likely effect?

Accepted Answer

DNA polymerase would frequently dissociate from the DNA, reducing replication efficiency.

Question 19

Which of the following best describes complementary base pairing in DNA?

Accepted Answer

A pairs with T, and G pairs with C

DNA Structure and Replication: Study Guide

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