Final answer:
When cells stop dividing, they can enter senescence, initiate programmed cell death, or undergo unregulated division leading to tumors and cancer. Terminally differentiated cells are cleared by apoptosis and replaced by stem cells. Accumulated mutations and shortened telomeres may trigger these outcomes.
Step-by-step explanation:
When certain cells stop dividing, several events can occur. First, a cell may progress into an irreversible state of dormancy known as senescence. This is when a cell no longer proliferates but still carries out some functions and is not dead.
Another possibility is for the cell to initiate programmed cell death, which is commonly referred to as apoptosis; this serves as a protective mechanism to eliminate dysfunctional cells.
Lastly, a cell may undergo unregulated cell division, which can lead to the formation of tumors and the potential development of cancer. This is often a result of mutations or errors in the cell's DNA that bypass normal regulatory mechanisms.
Cells that do not divide are referred to as terminally differentiated. An example would be red blood cells which have a limited lifespan and are constantly replenished from stem cells in the bone marrow. Terminally differentiated cells, when they reach the end of their effective lives, are typically cleared through apoptosis.
Mutations that accumulate in a cell's DNA can lead to senescence, apoptosis, or unregulated division. Cells with excessive DNA damage or critically short telomeres - protective caps at the ends of chromosomes - may lose their ability to divide.