What would happen if a large majority of an organism’s cells suddenly became diseased and died?

An event of uncontrolled cell death will lead to tissue damage and ultimately to organ failure. If it is not controlled, the organism can die.

What is necrosis?

A form of cell death which is not regulated or controlled by any mechanisms in the body. It leads to excess digestion of the cellular components. This results due to trauma at the cellular level which can be caused by environmental or physical factors.

The cells in the body die prematurely in this condition by the process of autolysis. There are a few environmental and physical factors that can induce necrosis. These are ischemia, thermal damage, infection, mechanical trauma etc.

This kind of cellular death is independent due to the apoptotic cell death pathway and is induced purely by external trauma. This causes an uncontrollable release of intracellular components into the extracellular region which induces an inflammatory response.

Therefore, an event of uncontrolled cell death will cause organ damage which can lead to death.