The internal structure of mitochondria

Electron microscopic (EM) tomography is providing important new insights in to the internal organization of mitochondria. The standard baffle model for cristae structure, called into question years ago, has now clearly been sh own to be inaccurate. Depending on source and conformational state, cristae can vary from simple tubular structures to more complex lamellar structure s merging with the inner boundary membrane through tubular structures 28 nm in diameter. The structural information provided by EM tomography has impo rtant implications for mitochondrial bioenergetics, biogenesis and the role of mitochondria in apoptosis. The structural paradigm defined by EM tomogr aphy is helping in the design of new experimental approaches to mitochondri al function.