G2 checkpoint

Definition

The G2 checkpoint is a critical control point in the cell cycle that occurs before a cell enters mitosis. This checkpoint ensures that the cell's DNA is fully replicated and that there are no DNA damages before the cell divides. If any issues are detected, the cell can delay progression or initiate repair mechanisms, highlighting its role in maintaining genomic integrity during cell division.

5 Must Know Facts For Your Next Test

1. The G2 checkpoint is crucial for preventing cells from entering mitosis with damaged or incompletely replicated DNA.
2. If DNA damage is detected at the G2 checkpoint, the cell can halt progression into mitosis and activate repair pathways to fix the damage.
3. Proteins such as p53 play a vital role at the G2 checkpoint by regulating cell cycle arrest in response to DNA damage.
4. The G2 checkpoint ensures that cells maintain their genetic integrity, which is important for preventing cancer and other diseases related to uncontrolled cell division.
5. Research indicates that mutations affecting components of the G2 checkpoint can lead to an increased risk of tumorigenesis due to unregulated cell cycle progression.

Review Questions

• How does the G2 checkpoint contribute to the overall regulation of the cell cycle?
  • The G2 checkpoint serves as a quality control mechanism that ensures cells do not proceed to mitosis with damaged or unreplicated DNA. By delaying cell division when issues are detected, it allows for DNA repair processes to take place, thus maintaining genomic stability. This checkpoint is critical for proper cell cycle regulation as it integrates signals from the environment and internal conditions to determine whether a cell is ready to divide.
• Discuss the role of proteins like p53 in the functioning of the G2 checkpoint.
  • Proteins such as p53 act as tumor suppressors that are essential for monitoring DNA integrity at the G2 checkpoint. When DNA damage is sensed, p53 can activate genes that lead to cell cycle arrest, allowing time for repair mechanisms to fix any issues. If the damage is irreparable, p53 may also trigger apoptosis, preventing the propagation of defective cells. This highlights how p53 helps maintain genomic stability during cell division.
• Evaluate how disruptions in the G2 checkpoint can lead to cancer development and other diseases.
  • Disruptions in the G2 checkpoint can have severe consequences for cellular health, as they allow cells with damaged DNA to progress into mitosis without proper repair. Such uncontrolled division can lead to an accumulation of mutations, contributing to tumorigenesis. Additionally, failure to adequately respond to DNA damage may result in chromosomal instability, which is a hallmark of many cancers. Understanding these disruptions emphasizes the importance of cell cycle checkpoints in preventing diseases linked to genetic abnormalities.

Related terms

Cell Cycle: The series of phases that a cell goes through leading to its division and replication, consisting of interphase (G1, S, G2) and mitosis.

Mitosis: The process by which a eukaryotic cell divides its nucleus and contents, resulting in two genetically identical daughter cells.

Cyclins:

Regulatory proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinases (CDKs).