Figure 2.

ROS production by the ETS. Electrons leak back into the mitochondrial matrix at CI, CII, and CIII and react with oxygen (O₂) to produce superoxide (∙O₂⁻). Superoxide is converted to hydrogen peroxide (H₂O₂) by the antioxidant superoxide dismutase (SOD), and H₂O₂ is converted to water (H₂O) by antioxidants GPx, thioredoxin reductase (TrxR), and catalase (CAT). Without proper sequestration by antioxidants, ∙O₂⁻ and H₂O₂ may damage proteins, lipids, and DNA, which can cause oxidative stress if left unchecked. Created with BioRender.com.