Figure 1. Illustration of key differences between the redox stress and oxidative damage mechanisms contributing to mitochondrial aging.

In the redox stress hypothesis an increase in oxidative stress leads to reversible regulatory changes in function that are dependent on the interaction between the mitochondria and the cell environment. In contrast, oxidative damage results in structural changes to macromolecules that are generally irreversible. The gradient on the bottom illustrates the continuum between healthy redox homeostasis and pathology.