Question 1

Which of the following correctly describes the difference between purines and pyrimidines in nucleic acids?

Accepted Answer

Purines have a double-ring structure, while pyrimidines have a single-ring structure.

Question 2

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

Accepted Answer

Helicase

Question 3

Which of the following base pairs is stabilized by three hydrogen bonds?

Accepted Answer

Guanine-Cytosine

Question 4

What is the direction of DNA synthesis by DNA polymerase?

Accepted Answer

$$5' \rightarrow 3'$$

Question 5

Which of the following best explains why DNA synthesis is 'discontinuous' on the lagging strand?

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end, so the lagging strand is synthesized in short fragments.

Question 6

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

Ligase

Question 7

A mutation causes the loss of function in single-stranded binding proteins (SSBPs) during DNA replication. What is the most likely consequence?

Accepted Answer

DNA strands will re-anneal, preventing replication.

Question 8

Which of the following is a correct description of the difference between DNA replication in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes have multiple origins of replication, while prokaryotes typically have a single origin.

Question 9

Which of the following best describes the role of primase in DNA replication?

Accepted Answer

It synthesizes short RNA primers to provide a starting point for DNA polymerase.

Question 10

If a DNA molecule has 20% adenine, what percentage of guanine does it contain?

Accepted Answer

30%

Question 11

Which of the following is the correct sequence of events during DNA replication?

Accepted Answer

Helicase unwinds DNA, primase synthesizes RNA primer, DNA polymerase extends DNA, ligase joins fragments.

Question 12

Which of the following best explains the semi-conservative nature of DNA replication?

Accepted Answer

Each new DNA molecule consists of one old strand and one newly synthesized strand.

Question 13

What is the function of topoisomerase during DNA replication?

Accepted Answer

It relieves supercoiling tension ahead of the replication fork.

Question 14

Which of the following is the correct complementary base pair for cytosine in DNA?

Accepted Answer

Guanine

Question 15

A scientist is analyzing a DNA strand and finds that the 5' end is associated with a phosphate group. What is the chemical group found at the 3' end?

Accepted Answer

Hydroxyl group ($$-OH)$$

Question 16

Which of the following best describes the role of DNA polymerase III in prokaryotic DNA replication?

Accepted Answer

It synthesizes the majority of the new DNA strand by adding nucleotides to the 3' end.

Question 17

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand during replication.

Question 18

Which of the following is NOT a component of a nucleotide in DNA?

Accepted Answer

Ribose sugar

Question 19

A patient is diagnosed with a genetic disorder that affects the function of DNA ligase. Which process would be most directly impaired?

Accepted Answer

Joining of Okazaki fragments on the lagging strand

Question 20

Which of the following best describes the energy source for DNA polymerization?

Accepted Answer

Hydrolysis of the phosphate bonds in deoxynucleoside triphosphates ($$dNTPs)$$

DNA Structure and Replication: Study Guide Notes

Study Guide - Practice Questions