Part 3/9:
Mitochondria are central to eukaryotic life, acting as cellular power stations. They produce energy through respiration by creating a voltage across their membranes, a process involving complex proteins that pump protons and synthesize ATP via a rotary nanomotor—the ATP synthase. This machinery is remarkably conserved across all life, from bacteria to humans, indicating its ancient origin. The universality of this energy system points back to a common ancestor and raises questions about how such a sophisticated system originated.