See work by Taanman in [38]. The light (L) strand encodes for eight tRNAs and a single polypeptide. The 13 protein products are subunits of the enzyme complexes of the respiratory chain/oxidative phosphorylation system (DiMauro and Schon, 2003) [37]. Mammalian mtDNA does not have introns, and has only a few intergenic sequences. The displacement loop (D-loop) region is a short, three-stranded structure in which a short nucleic acid strand, complementary to the L-strand, displaces the H-strand. The D-loop is the major control site for mtDNA expression, containing the leading-strand origin of replication and the major promoters for transcription [38].