The mitochondrial genome is the genetic material of the mitochondria. The mitochondria are organelles that reproduce themselves semi-autonomously when the eukaryotic cells that they occupy divide.
The genetic material forming the mitochondrial genome is similar in structure to that of the prokaryotic genetic material. It is formed of a single circular DNA molecule.
The mitochondria of a sexually-reproducing animal comes only from the mother's side. The mitochondrial DNA of a human being is essentially the same as that of his or her mother.
In this way, mitochondrial genetic diseases can affect both males and females, but can only be transmitted by females to their offspring.
Compared to the nuclear genome, the mitochondrial genome possesses some very interesting features:
- All the genes are carried on a single circular DNA molecule.
- The genetic material is not bounded by a nuclear envelope.
- The DNA is not packed with proteins.
- The genome doesn't contain a lot of non-coding (junk DNA) areas.
- Some codons do not follow the universal rules in translation.
- Some bases are considered as a part of two different genes: as the last base of a gene and the first base of the next gene.
