Radiation primarily affects mitosis by causing DNA damage, which can lead to cell death if unrepaired, particularly during cell division.
Here's a more detailed breakdown:
-
DNA Damage: Radiation, especially ionizing radiation, can directly damage DNA molecules. This damage can take various forms, including single-strand breaks, double-strand breaks, and base modifications.
-
Mitotic Arrest: When cells with damaged DNA attempt to undergo mitosis, checkpoint mechanisms within the cell cycle detect the damage. These checkpoints halt the cell cycle, preventing the cell from dividing until the damage is repaired. This is known as mitotic arrest.
-
Repair or Cell Death: If the DNA damage is successfully repaired, the cell can resume mitosis and complete cell division. However, if the damage is too severe or cannot be repaired, the cell may undergo one of two processes:
- Apoptosis (Programmed Cell Death): The cell initiates a controlled self-destruction program to prevent the propagation of damaged DNA.
- Necrosis: This is a form of cell death that occurs due to overwhelming damage. In the context of radiation, necrosis often results from cells with unrepaired DNA breaks attempting to pass through mitosis.
-
Consequences of Unrepaired Damage: If a cell with damaged DNA manages to divide, the resulting daughter cells may have mutations or chromosomal abnormalities. These abnormalities can lead to various problems, including uncontrolled cell growth (cancer) or cell dysfunction.
In summary, radiation disrupts mitosis primarily by damaging DNA. This damage can trigger mitotic arrest, giving the cell an opportunity to repair the damage. If repair fails, the cell will likely undergo apoptosis or necrosis, preventing the propagation of damaged genetic material. However, if the cell divides with unrepaired damage, it can lead to mutations and genomic instability.
