Nociceptors have a protective function. what is that function?

Nociceptors are pain receptors. They respond to stimuli that are dangerous to the body. Like if you put your hand on a hot surface. It burns. You are sending a signal to the cns to use your reflexes to pull the hand away from the hot surface.

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.