Q: Which of the following equations correctly represents the semi-conservative model of DNA replication?

$$\text{Parent DNA} \rightarrow \text{1 Parent Strand} + \text{1 New Strand}$$

Question 1

Which of the following best describes the primary function of cell cycle checkpoints?

Accepted Answer

To sense defects and prevent the progression of the cell cycle until certain conditions are met

Question 2

A mutation in the Rb gene is most likely to result in which of the following outcomes?

Accepted Answer

Uncontrolled progression from G1 to S phase, increasing the risk of tumorigenesis

Question 3

Which of the following statements about p53 is correct?

Accepted Answer

p53 is activated in response to DNA damage and can induce cell cycle arrest or apoptosis

Question 4

In the context of DNA replication origins, which of the following is a key feature of the bacterial origin of replication (oriC)?

Accepted Answer

It contains AT-rich sequences and DnaA boxes required for initiator protein binding

Question 5

A patient inherits one mutant allele of the Rb gene. Which of the following best describes their risk for retinoblastoma?

Accepted Answer

They are at increased risk and may develop tumors at a young age, often in both eyes

Question 6

Which of the following best explains why DNA replication origins are AT-rich?

Accepted Answer

AT base pairs have fewer hydrogen bonds, making the DNA easier to unwind

Question 7

What is the role of Dam methylation in E. coli DNA replication?

Accepted Answer

It is required for the recognition of the origin by DnaA and for the initiation of replication

Question 8

Which of the following equations correctly represents the semi-conservative model of DNA replication?

Accepted Answer

$$	ext{Parent DNA} ightarrow 	ext{1 Parent Strand} + 	ext{1 New Strand}$$

Question 9

A cell with a loss-of-function mutation in both alleles of p53 is most likely to:

Accepted Answer

Fail to arrest the cell cycle, allowing replication of damaged DNA

Question 10

Which of the following best describes the difference between cis-acting elements and trans-acting factors in DNA replication?

Accepted Answer

Cis-acting elements are DNA sequences, while trans-acting factors are proteins that bind to these sequences

Question 11

In eukaryotic DNA replication, what is the function of the Origin Recognition Complex (ORC)?

Accepted Answer

It binds to ARS elements and marks the site for replication initiation

Question 12

A researcher observes that only 15% of replication origins are active at the same time in a eukaryotic cell. What is the most likely explanation for this observation?

Accepted Answer

Origins are activated in a coordinated manner to ensure efficient and regulated DNA replication

Question 13

Which of the following is a direct consequence of a nonfunctional tumor suppressor gene?

Accepted Answer

Uncontrolled cell proliferation and increased risk of cancer

Question 14

During the G1-S checkpoint, which of the following is checked by the cell?

Accepted Answer

Sufficient growth and DNA damage repair

Question 15

Which of the following best explains why loss-of-function mutations in both Rb alleles are required for tumor development?

Accepted Answer

Both alleles must be inactivated because Rb is a recessive tumor suppressor gene

Question 16

Which of the following best describes the process of licensing in eukaryotic DNA replication?

Accepted Answer

Recruitment of helicase to the origin to form the pre-replication complex

Question 17

A cell is unable to re-enter the cell cycle after DNA damage. Which pathway is most likely activated?

Accepted Answer

Programmed cell death (apoptosis) pathway

Question 18

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

Accepted Answer

Bacterial origins are typically single per chromosome, while eukaryotic chromosomes have multiple origins

Question 19

Which of the following best describes the role of E2F transcription factors in the cell cycle?

Accepted Answer

They activate the expression of genes required for DNA synthesis and S phase entry

Question 20

A cell with constitutively active Ras is most likely to:

Accepted Answer

Continuously progress through the cell cycle, increasing the risk of cancer

Cell Cycle Checkpoints and DNA Replication Initiation

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