$$\text{Protein} + \text{ATP} \rightarrow \text{Protein-P} + \text{ADP}$$

Question 1

During which phase of the cell cycle does DNA replication occur, resulting in two sister chromatids per chromosome?

Accepted Answer

S phase

Question 2

What is the primary function of cyclin-dependent kinases (CDKs) in the cell cycle?

Accepted Answer

To phosphorylate proteins and promote progression through cell cycle checkpoints

Question 3

Which protein acts as an inhibitor of cell cycle progression at the G1/S checkpoint until it is phosphorylated?

Accepted Answer

Retinoblastoma protein (RB)

Question 4

A cell exposed to UV radiation activates p53, which leads to the production of p21. What is the consequence of p21 binding to cyclin-CDK complexes?

Accepted Answer

Cell cycle is halted and apoptosis may occur

Question 5

Which of the following best describes the role of the spindle apparatus during mitosis?

Accepted Answer

It separates sister chromatids to opposite poles of the cell

Question 6

What is the result of mitosis in terms of genetic material?

Accepted Answer

Two cells with identical genetic material to the parent cell

Question 7

Which checkpoint ensures that all chromosomes are properly attached to the spindle before the cell proceeds to anaphase?

Accepted Answer

M checkpoint

Question 8

How do growth factors stimulate the cell cycle?

Accepted Answer

By activating signal transduction pathways that lead to cyclin production

Question 9

Which of the following is an example of allosteric activation in the cell cycle?

Accepted Answer

Cyclin binding to CDK and opening its active site

Question 10

If a cell fails the G2/M checkpoint due to incomplete spindle formation, what is the most likely outcome?

Accepted Answer

The cell will pause and attempt to repair or complete spindle assembly

Question 11

Which molecule is responsible for phosphorylating RB, thereby allowing the cell to pass the restriction point?

Accepted Answer

Cyclin-dependent kinase (CDK)

Question 12

What is the main difference between mitosis and cytokinesis?

Accepted Answer

Mitosis divides the nucleus, cytokinesis divides the cytoplasm

Question 13

Which phase of mitosis is characterized by the alignment of chromosomes at the metaphase plate?

Accepted Answer

Metaphase

Question 14

A mutation in the gene encoding p53 would most likely result in which cellular consequence?

Accepted Answer

Uncontrolled cell division and increased cancer risk

Question 15

Which equation correctly represents the phosphorylation reaction catalyzed by CDK?

Accepted Answer

$$	ext{Protein} + 	ext{ATP} ightarrow 	ext{Protein-P} + 	ext{ADP}$$

Question 16

Which of the following best explains why cells undergo apoptosis after failing a checkpoint?

Accepted Answer

To prevent propagation of damaged or mutated DNA

Question 17

What is the role of the restriction point in the cell cycle?

Accepted Answer

It is the point at which the cell commits to DNA replication and division

Question 18

Which of the following would most likely occur if cyclin levels remain abnormally high throughout the cell cycle?

Accepted Answer

Uncontrolled cell division and potential tumor formation

Question 19

In a cancer cell, which of the following is most likely defective, leading to unchecked cell division?

Accepted Answer

Cell cycle checkpoints

Question 20

Which of the following is a direct result of cyclin binding to CDK?

Accepted Answer

CDK is allosterically activated and can phosphorylate target proteins

Cell Cycle Regulation, Mitosis, and Cancer: Structured Study Notes

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