 Tetrahymenothemophila is a classic ciliate model organism with tubular mitochondria containing Christi. It was found to have a highly diverged electron transport chain consisting of four transmembrane proteins, one to four, which were structurally characterized by Creo-electron microscopy. The results revealed two distinct mega-complexes, one composed of four copies of complex 4, civilian 2+, I+, 3, 2+, 2, 2, and another composed of four copies of complex I, I+, 3, 2+, 2, and three copies of complex 4, for 2+, I+, 3, 2+, 2, 2. These mega-complexes are arranged in a half-ring shape around the mitochondrion's curved surface, allowing for efficient transfer of electrons from complex 4 to complex I. This study provides insight into the evolution of mitochondrial morphology and electron transport chain diversification. This article was authored by Fan Zhuhan, Ichihu, Mengchen Wu, and others. We are article.tv, links in the description below.