The animation shows a simplified mitochondrion model with tubular invaginations (cristae) of the inner mitochondrial membrane. These invaginations increase the membrane area and thus the working efficiency of the mitochondrion which is an energy producing organelle. Mitochondria with tubular cristae are not as common as those with the elongated cristae. The outer mitochondrial membrane, which is much more permeable as the inner membrane, is shown as blue patches.
