- cells take high-energy electrons and release their energy in a controlled manner
- the body passes electrons to oxygen
- but oxygen is impatient and wants the high-energy electrons
- ca. 1-2% of the high-energy electrons are grabbed by oxygen
- oxygen turns into hulk: superoxid type of free radical
- superoxid is out of control, smashes around the cell, is damaging the DNA: Mitochondrial theory of aging
- this process is also called oxidative stress