$$\text{dNTP} + \text{(DNA)}_{n} \rightarrow \text{(DNA)}_{n+1} + \text{PP}_i$$

Question 1

Which property is NOT required for a molecule to serve as genetic material in cells?

Accepted Answer

It must be able to catalyze metabolic reactions.

Question 2

What is the main evidence supporting the semi-conservative model of DNA replication from the Meselson-Stahl experiment?

Accepted Answer

After one round of replication, DNA migrated at an intermediate position in a CsCl density gradient.

Question 3

Which equation best represents the formation of a phosphodiester bond during DNA synthesis?

Accepted Answer

$$	ext{dNTP} + 	ext{(DNA)}_{n} ightarrow 	ext{(DNA)}_{n+1} + 	ext{PP}_i$$

Question 4

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 5

Why does DNA polymerase require a primer to begin synthesis?

Accepted Answer

It needs a free 3’ OH group.

Question 6

Which direction does DNA polymerase synthesize new DNA?

Accepted Answer

5’ to 3’

Question 7

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

Accepted Answer

They keep the template strands separated.

Question 8

Which enzyme removes supercoils introduced during DNA replication?

Accepted Answer

Topoisomerase

Question 9

In eukaryotic chromosomes, what is the primary function of telomeres?

Accepted Answer

To protect chromosome ends from loss during replication.

Question 10

Which enzyme solves the 'end-replication problem' in eukaryotes by extending chromosome ends?

Accepted Answer

Telomerase

Question 11

What is the role of the RNA component in telomerase?

Accepted Answer

It serves as a template for adding telomeric repeats.

Question 12

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

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

Question 13

Which activity allows DNA polymerase to 'proofread' and correct errors during DNA replication?

Accepted Answer

3’ to 5’ exonuclease activity

Question 14

A diploid organism has two sets of chromosomes organized as homologous pairs. What is the significance of having two alleles (A and a) for a gene?

Accepted Answer

It enables genetic variation in traits such as hair color.

Question 15

Which model organism is commonly used to study DNA replication in prokaryotes?

Accepted Answer

Escherichia coli (E. coli)

Question 16

What is the consequence of the 'end-replication problem' if telomerase is not active in a cell?

Accepted Answer

Chromosome ends will be gradually shortened, potentially leading to loss of important genetic information.

Question 17

Which of the following statements about DNA polymerase is FALSE?

Accepted Answer

It can synthesize DNA de novo without a primer.

Question 18

In the Meselson-Stahl experiment, what would be the expected result after two rounds of replication if DNA replication were conservative?

Accepted Answer

Half DNA would be heavy, half would be light.

Question 19

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5’ to 3’ direction, so the lagging strand is synthesized in short segments.

Question 20

Which of the following is NOT a function of DNA polymerase I in E. coli DNA replication?

Accepted Answer

Joining Okazaki fragments.

DNA Replication: Mechanisms and Molecular Basis

Study Guide - Practice Questions