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

It acts as the first initiator protein complex that binds to origins of replication to assemble the prereplication complex.

Question 3

Which DNA polymerase is responsible for the processive elongation of the leading strand during eukaryotic DNA replication?

Accepted Answer

DNA polymerase $$ \epsilon $$

Question 4

What is the role of flap endonuclease during lagging strand synthesis in eukaryotes?

Accepted Answer

It removes RNA primers by cleaving the short flap structure created when DNA polymerase $$ \delta $$ displaces the primer.

Question 5

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

Accepted Answer

$$	ext{ATTTATGTTTA}$$

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 due to incomplete licensing of replication origins.

Question 7

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

Accepted Answer

DNA polymerase $$ \gamma $$

Question 8

What is the Hayflick effect, and how is it related to telomere length?

Accepted Answer

It is the phenomenon where cells lose their ability to divide after a certain number of divisions due to telomere shortening.

Question 9

Which of the following best describes the function of telomerase?

Accepted Answer

It adds repetitive DNA sequences to the ends of linear chromosomes to prevent shortening during replication.

Question 10

A cancer cell line is found to have highly active telomerase. What is the most likely consequence of this activity?

Accepted Answer

The cell line will maintain telomere length and continue dividing indefinitely.

Question 11

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

Accepted Answer

Eukaryotes have multiple origins of replication per chromosome, while prokaryotes typically have one.

Question 12

If a mutation prevents the polymerase switch from DNA polymerase $$ \alpha  to$$ $$ \epsilon  or$$ $$ \delta $$, what is the most likely outcome?

Accepted Answer

Elongation of the leading and lagging strands will be impaired, stalling DNA replication.

Question 13

Which enzyme is responsible for cleaving long flaps that cannot be processed by flap endonuclease during lagging strand synthesis?

Accepted Answer

Dna2 nuclease/helicase

Question 14

A researcher observes that a cell line accumulates DNA damage at chromosome ends and enters senescence prematurely. Which defect is most likely responsible?

Accepted Answer

Deficiency in telomerase activity

Question 15

Which of the following best describes the composition of the RNA-DNA hybrid primer synthesized during eukaryotic DNA replication?

Accepted Answer

10 RNA nucleotides followed by 20-30 DNA nucleotides

Question 16

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

Accepted Answer

They synthesize DNA across regions of damage, allowing replication to continue.

Question 17

If a eukaryotic cell lacked functional ARS elements, what would be the most likely result?

Accepted Answer

Replication origins would not be recognized, leading to incomplete DNA replication.

Question 18

Which of the following best explains why telomeres shorten with each cell division in most somatic cells?

Accepted Answer

DNA polymerase cannot fully replicate the 3' end of the lagging strand, leading to progressive shortening.

Question 19

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

Accepted Answer

Unlimited replicative potential due to maintenance of telomere length

Eukaryotic DNA Replication and Telomere Biology

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