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 bidirectionally 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 called oriC. Which specific sequence motifs within oriC are essential for the initiation of replication?

Accepted Answer

Conserved 13-mer and 9-mer sequences.

Question 4

Which consensus sequence is found in the 9-mer region of bacterial origins of replication, such as in E. coli?

Accepted Answer

TTATCCACA

Question 5

During DNA replication, what is the role of Okazaki fragments?

Accepted Answer

They are short DNA segments synthesized on the lagging strand.

Question 6

Why does the lagging strand require multiple RNA primers during DNA replication?

Accepted Answer

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

Question 7

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

Accepted Answer

DNA ligase

Question 8

Eukaryotic chromosomes have multiple origins of replication. What is the main advantage of this feature?

Accepted Answer

It allows for faster and more efficient replication of large genomes.

Question 9

If a mutation occurred in the 9-mer consensus sequence of oriC in E. coli, which of the following would most likely result?

Accepted Answer

Replication initiation would be impaired due to reduced binding of initiator proteins.

Question 10

Which of the following best explains why DNA replication in bacteria is considered semiconservative?

Accepted Answer

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

Question 11

A researcher is studying DNA replication in human cells. She observes that replication origins are spaced approximately every 100,000 base pairs. If the human genome is roughly $$3 	imes 10^9$ base pairs, estimate the minimum number of replication origins required for complete replication.

Accepted Answer

$$30,000$$

Question 12

Which of the following statements about the replication fork is correct?

Accepted Answer

The leading strand is synthesized continuously in the same direction as fork progression.

Question 13

In a circular bacterial chromosome, what would happen if the two replication forks failed to meet at the terminus site?

Accepted Answer

The chromosome would remain partially replicated, leading to incomplete genetic material.

Question 14

Which of the following is NOT a feature of the origin of replication in bacteria?

Accepted Answer

It is found at multiple locations on the chromosome.

Question 15

A mutation in the gene encoding DNA ligase would most likely result in which of the following defects during DNA replication?

Accepted Answer

Failure to join Okazaki fragments on the lagging strand.

Question 16

Which of the following best describes the difference between bacterial and eukaryotic DNA replication origins?

Accepted Answer

Bacteria typically have a single origin of replication, while eukaryotes have multiple origins per chromosome.

Question 17

If the consensus 9-mer sequence in a bacterial origin of replication is altered, which process would be most directly affected?

Accepted Answer

Binding of initiator proteins and initiation of DNA replication.

Question 18

Which of the following is true regarding the directionality of DNA synthesis at the replication fork?

Accepted Answer

DNA polymerase synthesizes new DNA in the 5' to 3' direction on both leading and lagging strands.

Question 19

A student claims that Okazaki fragments are found on both the leading and lagging strands during DNA replication. Is this statement correct?

Accepted Answer

No, Okazaki fragments are only found on the lagging strand.

DNA Replication: Mechanisms and Origins in Prokaryotes and Eukaryotes

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