Intermembrane space

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Definition

The intermembrane space is a space between the two membranes of a mitochondrion: the outer mitochondrial membrane and inner mitochondrial membrane.

Summary

Item Value
Type of organisms whose cells contain the intermembrane space Same as the 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 intermembrane space 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 intermembrane spaces per cell Same as the number of mitochondria: 1 to 1000s, depending on the energy needs of the cell
Size angstrom or thickness (very approximate), accounting for less than 5% of the diameter (less than 10% even if you consider that it's on both sides).
Location within the mitochondrion It is right inside of the boundary of the mitochondrion (the boundary is the outer mitochondrial membrane).
What's on both sides of it Inside: inner mitochondrial membrane, outside: outer mitochondrial membrane
Structural components The intracristal space is the part of the intermembrane space between the folds (cristae) of the inner mitochondrial membrane. The peripheral space is the part of the intermembrane space farther out of the inner mitochondrial membrane.
pH About 7.0 to 7.4. Although still a little alkaline, it is less so than the mitochondrial matrix and less so than the rest of the cell, due to the pumping out of protons from the mitochondrial matrix as part of the electron transport chain.