Mitochondrial matrix
This article describes a component of the organelle mitochondrion in cells.
Unless otherwise specified, information about this component is about its in situ occurrence in vivo, i.e., its occurrence in its usual location in living cells.
Definition
The mitochondrial matrix is the interior part of the mitochondrion, specifically the part on the inside of the inner mitochondrial membrane. It comprises the bulk of the volume of the mitochondrion. The citric acid cycle occurs inside the mitochondrial matrix.
Summary
| Item | Value |
|---|---|
| Type of organisms whose cells contain the mitochondrial matrix | Same as the type of organisms whose cells contain mitochondria: eukaryotic cells only, including plant cells, animal cells, and the cells of protists and fungi |
| Type of cells within the organisms that contain the mitochondrial matrix | Same as the cells that contain mitochondria: All cells except red blood cells in mammals (other vertebrates do have mitochondria in their red blood cells). |
| Number of mitochondrial matrices per cell | One per mitochondrion, so 1 to 1000s, depending on the energy needs of the cell |
| Size | diameter per mitochondrial matrix; this is over 90% of the diameter of the mitochondrion; the mitochondrial matrix is the bulk of the volume of the mitochondrion. |
| Location within mitochondrion | The mitochondrial matrix is located in the interior of the mitochondrion; it is bounded by the inner mitochondrial membrane that in turn is surrounded by the intermembrane space of mitochondrion, that in turn is bounded by the outer mitochondrial membrane. |
| Structural components | Mitochondrial DNA, ribosomes, soluble enzymes, small organic molecules, nucleotide cofactors, and inorganic ions |
| pH | About 7.8, compared with pH of 7.0 for water and pH of 7.0 to 7.4 for the intermembrane space. The high pH represents an alkaline environment, and is a result of the pumping out of protons via the electron transport chain. |
| Function | Most steps of cellular respiration occur inside the mitochondrial matrix; this includes the citric acid cycle, the electron transport chain (that effectively pumps protons out of the mitochondrial matrix into the intermembrane space of mitochondrion via the inner mitochondrial membrane), and oxidative phosphorylation (this involves pulling protons back into the mitochondrial matrix from the intermembrane space via the inner mitochondrial membrane). In addition, the mitochondrial matrix is involved with most other mitochondrial functions. |
