Mitochondria

A mitochondrion has outer and an inner membrane between which is the inter membrane space.  The  outer  membrane  contains  porin  proteins which  make it permeable  to molecules  of up to 10 kDa. The inner membrane, which is less permeable considerably, has large infolding known as cristae which generate into the central matrix.  The inner membrane is the site of oxidative phosphorylation and in ATP production electron transport involved. The central matrix is the site of numerous metabolic reactions including the citric acid cycle and fatty acid breakdown. Also within the matrix is found the mitochondrial DNA which encodes some of the mitochondrial proteins.