Question 1

Which of the following best explains why eukaryotic chromosomes require multiple origins of replication?

Accepted Answer

Eukaryotic chromosomes are linear and very large, so multiple origins ensure timely and complete DNA replication.

Question 2

What is the primary function of the Origin Recognition Complex (ORC) in eukaryotic DNA replication?

Accepted Answer

To act as the first initiator protein complex that binds to origins of replication and recruits other pre-replication complex proteins.

Question 3

Which DNA polymerase is responsible for synthesizing the leading strand during eukaryotic DNA replication?

Accepted Answer

DNA polymerase $$ \epsilon $$

Question 4

In eukaryotic DNA replication, what is the role of flap endonuclease?

Accepted Answer

It removes RNA primers from Okazaki fragments by cleaving the short flap structures created by DNA polymerase $$ \delta .$$

Question 5

Which of the following statements about telomerase is TRUE?

Accepted Answer

Telomerase contains both protein and RNA components, and extends the 3’ overhang of telomeres.

Question 6

A mutation in the gene encoding MCM helicase would most likely result in which of the following?

Accepted Answer

Failure to initiate DNA synthesis at origins due to inability to unwind DNA.

Question 7

Which of the following best describes the ARS elements in Saccharomyces cerevisiae?

Accepted Answer

They are about 50 bp in length, rich in A and T, and serve as origins of replication.

Question 8

During eukaryotic DNA replication, what is the consequence if the problem at the ends of linear chromosomes is not solved?

Accepted Answer

Chromosomes will become progressively shorter, eventually leading to loss of essential genetic information.

Question 9

Which DNA polymerase is primarily responsible for mitochondrial DNA replication in eukaryotes?

Accepted Answer

DNA polymerase $$ \gamma $$

Question 10

A patient’s cancer cells are found to have abnormally high telomerase activity. Which of the following is the most likely consequence?

Accepted Answer

The cancer cells will maintain their telomere length, allowing them to divide indefinitely.

Question 11

Which of the following best describes the polymerase switch during eukaryotic DNA replication?

Accepted Answer

The replacement of DNA polymerase $$ \alpha $$ with DNA polymerase $$ \epsilon  or$$ $$ \delta $$ for elongation of the leading and lagging strands.

Question 12

Which of the following is a key difference between eukaryotic and prokaryotic DNA replication?

Accepted Answer

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

Question 13

A scientist is studying a eukaryotic cell line with a mutation that inactivates flap endonuclease. What is the most likely result during DNA replication?

Accepted Answer

RNA primers on the lagging strand will not be removed, resulting in incomplete DNA fragments.

Question 14

Which of the following sequences is most likely to be found at an ARS element in yeast?

Accepted Answer

$$ATTTATGTTTA$$

Question 15

Which step is NOT part of the enzymatic action of telomerase?

Accepted Answer

Removal of RNA primers from Okazaki fragments.

Question 16

A cell is observed to have very short telomeres and has stopped dividing. What is the most likely explanation?

Accepted Answer

The cell has become senescent due to telomere shortening.

Question 17

Which of the following is a function of translesion-replicating DNA polymerases in eukaryotes?

Accepted Answer

They replicate over damaged DNA regions, allowing DNA synthesis to continue past lesions.

Question 18

If a mutation prevents the binding of the Origin Recognition Complex (ORC) to DNA, what is the most likely outcome?

Accepted Answer

The pre-replication complex (preRC) will not assemble, and DNA replication will not initiate at origins.

Question 19

Which of the following best explains why telomerase is a potential target for anti-cancer drug treatments?

Accepted Answer

Inhibiting telomerase would cause cancer cells to lose their telomeres and stop dividing.

Eukaryotic DNA Replication: Mechanisms, Enzymes, and Telomere Maintenance

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