G2 Phase

Definition

The G2 phase is a crucial stage in the cell cycle where the cell undergoes final preparations for mitosis after DNA replication during the S phase. During this phase, the cell ensures that all DNA has been accurately replicated and repairs any DNA damage, making it essential for maintaining genetic stability before division.

5 Must Know Facts For Your Next Test

1. The G2 phase typically lasts several hours to a few days, depending on the cell type and environmental conditions.
2. During G2, the cell synthesizes proteins necessary for mitosis and duplicates organelles to ensure each daughter cell has the required components.
3. G2 includes critical checkpoints where the cell assesses DNA integrity and can trigger repair mechanisms or induce apoptosis if severe damage is detected.
4. The cyclin-dependent kinases (CDKs) play a significant role during the G2 phase by regulating progression into mitosis through phosphorylation of target proteins.
5. Cells that pass through the G2 checkpoint without issues proceed to mitosis, while those with unresolved problems may enter a quiescent state or undergo programmed cell death.

Review Questions

• How does the G2 phase contribute to the overall integrity of the cell cycle?
  • The G2 phase plays a vital role in maintaining genetic integrity within the cell cycle by providing time for DNA repair and ensuring complete replication. During this phase, the cell conducts thorough checks for DNA damage and repairs any discrepancies before moving on to mitosis. This quality control mechanism helps prevent the propagation of genetic errors, ultimately safeguarding against potential malfunctions in cellular processes.
• Discuss the regulatory mechanisms involved in the transition from G2 phase to mitosis.
  • The transition from G2 phase to mitosis is tightly regulated by various cyclin-dependent kinases (CDKs) and their corresponding cyclins. These proteins control key checkpoints that assess whether DNA has been accurately replicated and whether there are any errors present. If conditions are favorable, CDKs phosphorylate target proteins that trigger the onset of mitosis. If issues are detected, signaling pathways can lead to temporary arrest in G2 until repairs are made or result in apoptosis if damage is irreparable.
• Evaluate the consequences of a malfunctioning G2 checkpoint on cellular division and organismal health.
  • A malfunctioning G2 checkpoint can have severe consequences on cellular division and overall organism health. If cells proceed to mitosis without properly repaired DNA, it can lead to aneuploidy or mutations in daughter cells, potentially resulting in cancerous growths or other genetic disorders. The accumulation of such errors can disrupt normal tissue function and contribute to various diseases, highlighting the importance of robust checkpoint mechanisms in maintaining cellular integrity throughout the life of an organism.

Related terms

Mitosis: The process of cell division where a single cell divides to produce two genetically identical daughter cells.

Cell Cycle: The series of phases that a cell goes through from its formation to the point it divides into two daughter cells, including G1, S, G2, and M phases.

Checkpoint: Regulatory mechanisms in the cell cycle that ensure proper progression through the stages by checking for errors or damage before proceeding.