Figure 4.

Human mitochondrium is a double membrane-bound organelle found in the cytoplasm. It usually contains several copies of mtDNA, which is a closed double-stranded DNA having heavy (H) and light (L) strands. It has 13 polypeptide encoding genes – Cytb, ND1-6, ND4l, ATPase 6 and 8, COI-III – whose products are components of the mitochondrial electron transport chain. Other genes of mtDNA are 2 rRNA and 22 tRNA genes. Promoters (P) for these genes (2 for heavy strand and 1 for light strand) are located in a single regulatory region, where also the origin for heavy strand replication occurs (O_H)