Research Perspective Volume 1, Issue 8 pp 746—750

Figure 1. A simple diagram depicting electron transport in mammalian cells. The redox potential increases as the electrons move through each complex located in the inner membrane of the mitochondria. NADH, an electron donor, donates two electrons. The electrons flow through the four complexes causing hydrogen (H⁺) to be pumped across the inner mitochondrial membrane to favor free energy. At each step, the free electron can be picked up by oxygen (O₂), which will convert O₂ to superoxide, a highly reactive oxygen species (ROS). Electron transfer can be blocked at the complexes by several different compounds. Antimycin A blocks transfer of electrons at complex III.