an octahedron: basically two square based pyramids with their bases stuck together.
Most eukaryotic cells have mitochondria, which produce ATP from products of the citric acid cycle, fatty acid oxidation, and amino acid oxidation. At the mitochondrial inner membrane, electrons from NADH and succinate pass through the electron transport chain to oxygen, which is reduced to water.
Electron Transport Chain. A sequence of enzymes that act as electron carrier molecules that transfer electrons and release energy during cellular respiration to produce ATP from ADP.