G2 checkpoint

Definition

The G2 checkpoint is a critical control mechanism in the cell cycle that occurs at the end of the G2 phase, ensuring that the cell is fully prepared to enter mitosis. This checkpoint assesses DNA integrity, DNA replication completion, and overall cell size, allowing for the identification and repair of any damage before cell division occurs. By performing these checks, the G2 checkpoint plays a crucial role in preventing the transmission of genetic errors to daughter cells.

5 Must Know Facts For Your Next Test

1. The G2 checkpoint functions primarily to verify that DNA replication has been completed accurately without errors or damage.
2. If damage is detected during the G2 checkpoint, the cell cycle can be halted to allow for repair mechanisms to correct any issues.
3. Proteins such as cyclin-dependent kinases (CDKs) and cyclins play important roles in regulating the progression through the G2 checkpoint.
4. Failure of the G2 checkpoint can lead to uncontrolled cell division, which is a hallmark of cancer development.
5. This checkpoint is crucial for maintaining genetic stability; cells that bypass this control without proper repair can lead to mutations passed on to daughter cells.

Review Questions

• How does the G2 checkpoint contribute to maintaining genomic stability in cells?
  • The G2 checkpoint contributes to maintaining genomic stability by ensuring that any DNA damage is repaired before the cell proceeds to mitosis. By assessing whether DNA replication is complete and checking for any errors, this checkpoint prevents cells with damaged or incomplete DNA from dividing. This quality control measure helps protect against mutations that could arise from faulty DNA being passed on to daughter cells.
• What are some key proteins involved in the regulation of the G2 checkpoint, and how do they function?
  • Key proteins involved in regulating the G2 checkpoint include cyclin-dependent kinases (CDKs) and their associated cyclins. CDKs are activated when bound to cyclins, which leads to phosphorylation of target proteins necessary for cell cycle progression. These proteins help facilitate the transition from G2 to mitosis. If conditions are not right—such as if DNA damage is detected—the activity of these CDKs is inhibited, halting progression until issues are resolved.
• Evaluate the consequences of a defective G2 checkpoint on cellular health and organismal development.
  • A defective G2 checkpoint can have severe consequences on cellular health and organismal development. When this checkpoint fails, cells may proceed to divide with damaged or incomplete DNA, leading to mutations that can accumulate over time. This accumulation increases the risk of developing cancer and other diseases characterized by genetic instability. Furthermore, during organismal development, such defects can result in developmental abnormalities as improperly functioning cells proliferate uncontrollably.

Related terms

Cell Cycle: The series of phases that a cell goes through as it grows and divides, including G1, S, G2, and M phases.

M Checkpoint: Also known as the spindle checkpoint, this mechanism ensures that all chromosomes are properly aligned and attached to the spindle apparatus before proceeding to anaphase during mitosis.

DNA Damage Response:

A network of cellular pathways that detect and repair DNA damage, helping maintain genomic stability and prevent mutations.