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Components of a typical mitochondrion
The mitochondrial matrix also contains the mitochondria's DNA and ribosomes. The word "matrix" stems from the fact that this space is viscous, compared to the relatively aqueous cytoplasm. The cytosolic compartment has a water content of 3.8 μl/mg protein, while the mitochondrial matrix 0.8 μl/mg protein.1 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 7.8.2
The electron transport chain is located in the cristae of the inner mitochondrial membrane. The NADH and FADH2 produced by the citric acid cycle in the matrix release a proton and electron to regenerate NAD+ and FAD. Protons are pulled into the intermembrane space by the energy of the electrons going through the electron transport chain. Two electrons are finally accepted by oxygen in the matrix to complete the electron transport chain. The protons return to the mitochondrial matrix through the process of chemiosmosis through the protein ATP synthase.
- Soboll, S., Scholz, R., Freisl, M., Elbers, R. & Heldt, H. W. (1976). "Distribution of metabolites between mitochondria and cytosol of perfused liver". In J. M. Tager, Hans-Dieter Söling, John R. Williamson. Use of Isolated Liver Cells and Kidney Tubules in Metabolic Studies. New York: Elsevier. pp. 29–40. ISBN 978-0-444-10925-5. LCCN 76009093. OCLC 2137029.
- Porcelli, AM; Ghelli, A et al. (2005). "pH difference across the outer mitochondrial membrane measured with a green fluorescent protein mutant". Biochemical and Biophysical Research Communications 326 (4): 799–804. doi:10.1016/j.bbrc.2004.11.105. PMID 15607740