Structure of a mitochondrion showing the outer mitochondrial membrane, inner mitochondrial membrane, intermembrane space and the mitochondrial matrix. Mitochondrial genome residing in the mitochondrial matrix has 37 genes coding for 13 OXPHOS proteins (in red, **), 2 ribosomal RNAs (12s rRNA, 16s rRNA,*), 22 tRNAs (***) and a regulatory D loop region.