Editing Mitochondrial matrix (section)

{{short description|Space within the inner membrane of the mitochondrion}}
{{Cell biology|mitochondrion=yes}}
In the [[mitochondrion]], the '''matrix''' is the space within the [[Inner mitochondrial membrane|inner membrane]]. It can also be referred as the mitochondrial fluid. The word "matrix" stems from the fact that this space is viscous, compared to the relatively aqueous cytoplasm. The mitochondrial matrix contains the [[mitochondrial DNA]], [[ribosome]]s, soluble [[enzyme]]s, small organic molecules, [[nucleotide]] cofactors, and [[inorganic ions]].<sup>[1]</sup> The enzymes in the matrix facilitate reactions responsible for the production of [[Adenosine triphosphate|ATP]], such as the [[citric acid cycle]], [[oxidative phosphorylation]], oxidation of [[pyruvate]], and the [[Beta oxidation|beta oxidation of fatty acids]].<ref name=":0">{{Cite book|title=Fundamentals of Biochemistry Life at the Molecular Level|last1=Voet|first1=Donald|last2=Voet|first2=Judith|last3=Pratt|first3=Charlotte|publisher=John Wiley & Sons, Inc.|year=2013|isbn=978-1118129180|location=New York City|pages=582–584}}</ref>

The composition of the matrix based on its structures and contents produce an environment that allows the [[Anabolism|anabolic]] and [[Catabolism|catabolic]] pathways to proceed favorably. The [[electron transport chain]] and enzymes in the matrix play a large role in the [[citric acid cycle]] and [[oxidative phosphorylation]]. The [[citric acid cycle]] produces [[Nicotinamide adenine dinucleotide|NADH]] and [[Flavin adenine dinucleotide|FADH2]] through oxidation that will be reduced in [[oxidative phosphorylation]] to produce [[Adenosine triphosphate|ATP]].<ref name=":1">{{Cite book|title=Biochemistry|last1=Stryer|first1=L|last2=Berg|first2=J|last3=Tymoczko|first3=JL|publisher=W.H. Freeman|year=2002|isbn=978-0-7167-4684-3|location=San Francisco|pages=509–527, 569–579, 614–616, 638–641, 732–735, 739–748, 770–773}}</ref><ref>{{Cite journal|last1=Mitchell|first1=Peter|last2=Moyle|first2=Jennifer|date=1967-01-14|title=Chemiosmotic Hypothesis of Oxidative Phosphorylation|journal=Nature|language=en|volume=213|issue=5072|pages=137–139|doi=10.1038/213137a0|pmid=4291593|bibcode=1967Natur.213..137M |s2cid=4149605 }}</ref>

The cytosolic, [[intermembrane space]], compartment has a higher aqueous:protein content of around 3.8 μL/mg protein relative to that occurring in mitochondrial matrix where such levels typically are near 0.8 μL/mg protein.<ref name=":5">{{Cite book|title=Distribution of metabolites between mitochondria and cytosol of perfused liver|last1=Soboll|first1=S|last2=Scholz|first2=R|last3=Freisl|first3=M|last4=Elbers|first4=R|last5=Heldt|first5=H.W.|publisher=Elsevier|year=1976|isbn=978-0-444-10925-5|location=New york|pages=29–40}}</ref> It is not known how mitochondria maintain [[Osmosis|osmotic]] balance across the inner mitochondrial membrane, although the membrane contains [[aquaporin]]s that are believed to be conduits for regulated water transport. Mitochondrial matrix has a pH of about 7.8, which is higher than the pH of the intermembrane space of the mitochondria, which is around 7.0–7.4.<ref name=":6">{{Cite journal|last1=Porcelli|first1=Anna Maria|last2=Ghelli|first2=Anna|last3=Zanna|first3=Claudia|last4=Pinton|first4=Paolo|last5=Rizzuto|first5=Rosario|last6=Rugolo|first6=Michela|date=2005-01-28|title=pH difference across the outer mitochondrial membrane measured with a green fluorescent protein mutant|journal=Biochemical and Biophysical Research Communications|volume=326|issue=4|pages=799–804|doi=10.1016/j.bbrc.2004.11.105|pmid=15607740}}</ref> 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, and in humans is maternally derived. Mitochondria of mammals have 55s ribosomes.