Question 1

Which of the following best describes the semi-conservative model of DNA replication?

Accepted Answer

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

Question 2

During DNA replication, nucleotides are added to which end of the growing DNA strand?

Accepted Answer

3' hydroxyl end

Question 3

Which enzyme is responsible for synthesizing new DNA strands during replication?

Accepted Answer

DNA polymerase

Question 4

What is the primary function of primers in DNA replication?

Accepted Answer

To provide a starting point with a free 3' OH group for DNA polymerase

Question 5

Which of the following statements about PCR (Polymerase Chain Reaction) is TRUE?

Accepted Answer

PCR requires sequence-specific DNA primers and a heat-stable DNA polymerase.

Question 6

In the context of DNA replication, what is the role of dideoxynucleotides (ddNTPs) in Sanger sequencing?

Accepted Answer

They terminate DNA strand elongation by lacking a 3' OH group.

Question 7

Which of the following best explains why DNA synthesis proceeds in the 5' to 3' direction?

Accepted Answer

Because DNA polymerase requires a free 3' OH group to form a phosphodiester bond with the incoming nucleotide.

Question 8

A scientist wants to amplify a specific DNA sequence using PCR. Which of the following components is NOT required in the reaction mixture?

Accepted Answer

DNA ligase

Question 9

Which of the following is a key difference between DNA replication in cells and PCR?

Accepted Answer

DNA replication in cells uses RNA primers, while PCR uses DNA primers.

Question 10

If a double-stranded DNA molecule undergoes three cycles of PCR, how many copies of the target DNA sequence will be present (assuming 100% efficiency)? Use the formula $$N = N_0$ 	imes 2^n$$, where $$N_0 is $$the initial number of molecules and $$n is $$the number of cycles.

Accepted Answer

$$N = 1 	imes 2^3$ = 8$$

Question 11

Which of the following best describes the function of the replication origin in eukaryotic chromosomes?

Accepted Answer

It is the specific sequence where DNA synthesis is initiated.

Question 12

During DNA replication, the lagging strand is synthesized in short fragments known as:

Accepted Answer

Okazaki fragments

Question 13

Which of the following is a real-world application of PCR?

Accepted Answer

Screening blood products for viral infections

Question 14

Why is a heat-stable DNA polymerase (such as Taq polymerase) required for PCR?

Accepted Answer

Because it remains active after repeated heating cycles used to denature DNA.

Question 15

Which of the following best explains the significance of Rosalind Franklin's 'Photograph 51'?

Accepted Answer

It provided key evidence for the double helical structure of DNA.

Question 16

In a dideoxy sequencing reaction, what would happen if only normal deoxynucleotides (dNTPs) were present and no dideoxynucleotides (ddNTPs) were added?

Accepted Answer

DNA synthesis would continue to the end of the template without termination.

Question 17

Which of the following statements about the leading and lagging strands at a replication fork is correct?

Accepted Answer

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

Question 18

A mutation in the gene encoding DNA polymerase prevents the enzyme from recognizing the 3' OH group. What is the most likely consequence for DNA replication?

Accepted Answer

No new nucleotides will be added to the growing DNA strand.

Question 19

Which of the following is a key reason why eukaryotic chromosomes have multiple origins of replication?

Accepted Answer

To ensure that DNA replication is completed quickly and efficiently.

Question 20

Which of the following best describes the directionality of DNA strands in a double helix?

Accepted Answer

The two strands are antiparallel, one running 5' to 3' and the other 3' to 5'.

DNA Replication: Structure, Mechanism, and Applications

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