Mitochondrial matrix
The cytosolic, intermembrane space, compartment has a water content of 3.8 μl/mg protein, while the mitochondrial matrix 0.8 μl/mg protein. It is not known how mitochondria maintain osmotic balance across the inner mitochondrial membrane, although the membrane contains aquaporins that are believed to be conduits for regulated water transport. Mitochondrial matrix has a pH of about 7.8. Mitochondrial DNA was discovered by Nash and Margit in 1963. One to many double stranded mainly circular DNA is present in mitochondrial matrix. Mitochondrial DNA is 1% of total DNA of a cell. It is rich in Guanine and Cytosine content. Mitochondria of mammals have 55s ribosomes.
Most recent common ancestor
Mitochondrial DNA (mtDNA) is nearly immune to sexual mixing, unlike the nuclear DNA whose chromosomes are shuffled and recombined in Mendelian inheritance. Mitochondrial DNA, therefore, can be used to trace matrilineal inheritance and to find the Mitochondrial Eve (also known as the "African Eve"), the most recent common ancestor of all humans via the mitochondrial DNA pathway.