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.
Paternal mtDNA transmission
The mixing of maternal and paternal mtDNA was thought to have been found in chimpanzees in 1999 and in humans in 1999 and 2018, resulting this last finding quite impressive, as biparental mtDNA was observed in subsequent generations in three different familias, leading to the conclusion that, although the maternal transmission dogma remains strong, there is evidence that paternal transmission do exist and there is a probably a mechanism which, if elucidated, can be a new tool in reproductive field, for example, avoiding the mitochondrial replacement therapy, and just using this mechanism so that the offspring inherit the paternal mitochondria. However, there has been only a single documented case of 90% human paternal mitochondrial DNA transmission.