Fig. 2.

The structure of human mitochondrial DNA. As shown, mitochondrial DNA is circular, and it has 2 strands––a guanine-rich outer strand and cytosine-rich inner strand. The mitochondrial DNA is encoded by 13 polypeptide chains, which encode all essential components of ETC. The mitochondrial DNA also encodes the 22 tRNAs (which are indicated as capital letters outside of outer mitochondrial strand), 12S and 16S rRNA. D-loop represents the control region of mitochondrial DNA. The somatic mtDNA mutations have also been reported to be elevated in Parkinson’s disease (Ikebe et al. 1990; Ozawa et al. 1990), Huntington’s disease (Horton et al. 1995), AD (Corral-Debrinski et al. 1994), livers of alcoholics (Fromenty et al. 1995), ovaries of post-menopausal women (Fromenty et al. 1995), and reduced mobility sperm (Kao et al. 1995)