Question 1

Which of the following statements best describes the bidirectional replication of a circular bacterial chromosome?

Accepted Answer

Replication begins at a single origin and proceeds in both directions until the forks meet at the terminus.

Question 2

What is the primary function of the conserved A-T rich sequences at bacterial replication origins?

Accepted Answer

They attract replication enzymes to initiate DNA synthesis.

Question 3

In E. coli, the origin of replication is known as oriC. Which sequences within oriC are essential for the initiation of replication?

Accepted Answer

13-mer and 9-mer repeats

Question 4

Which consensus sequence is commonly found in the 9-mer region of bacterial origins of replication?

Accepted Answer

TTATCCACA

Question 5

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

Accepted Answer

Helicase

Question 6

What is the role of Okazaki fragments in DNA replication?

Accepted Answer

They are short DNA segments synthesized on the lagging strand.

Question 7

Which enzyme joins Okazaki fragments together during DNA replication?

Accepted Answer

DNA ligase

Question 8

Why is DNA replication more complex in eukaryotes compared to prokaryotes?

Accepted Answer

Eukaryotic genomes contain multiple linear chromosomes and thousands of replication origins.

Question 9

A mutation in the gene encoding DNA polymerase III’s 3'-to-5' exonuclease activity would most likely result in:

Accepted Answer

Increased rate of replication errors due to loss of proofreading.

Question 10

Which equation best represents the directionality of DNA synthesis by DNA polymerase?

Accepted Answer

$$5' \rightarrow 3'$$

Question 11

In eukaryotic cells, what problem arises during replication of linear chromosomes, and how is it solved?

Accepted Answer

The lagging strand cannot be fully replicated; telomerase extends telomeres to prevent loss of genetic information.

Question 12

Which of the following is a direct consequence of telomerase activation in somatic cells?

Accepted Answer

Potential for increased cell longevity and risk of cancer due to immortalization.

Question 13

Which step in the Polymerase Chain Reaction (PCR) involves the hybridization of primers to the target DNA?

Accepted Answer

Annealing

Question 14

During Sanger sequencing, what is the role of dideoxynucleotides (ddNTPs)?

Accepted Answer

They terminate DNA strand elongation at specific bases.

Question 15

Which of the following best explains why multiple replication origins are necessary in eukaryotic chromosomes?

Accepted Answer

Eukaryotic chromosomes are large and linear, requiring multiple origins to ensure timely replication.

Question 16

A researcher is studying a bacterial species with a mutated 9-mer sequence at its origin of replication. What is the most likely outcome?

Accepted Answer

Impaired initiation of DNA replication due to reduced binding of replication proteins.

Question 17

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

Accepted Answer

DNA polymerase I

Question 18

In a DNA replication bubble, which strand is synthesized continuously and in the same direction as the replication fork?

Accepted Answer

Leading strand

Question 19

Which of the following best describes the proofreading activity of DNA polymerase?

Accepted Answer

It uses a $$3' \rightarrow 5'$$ exonuclease activity to remove mismatched nucleotides.

Question 20

A patient’s cancer cells show high telomerase activity. What is the most likely effect on these cells?

Accepted Answer

The cells can divide indefinitely due to stabilized chromosome ends.

DNA Replication: Mechanisms and Origins in Prokaryotes and Eukaryotes

Study Guide - Practice Questions