Mitochondria are enclosed by a double-membrane system made up of an inner and an outer membrane. The space between these two membranes is called (surprise!) the intermembrane space. The inner membrane encloses the interior of the mitochondrion, which is known as the mitochondrial matrix.The inner membrane also forms a large number of folds, called cristae, that extend into the matrix.See Fig.he space between these two membranes is called (surprise!) the intermembrane space. The inner membrane encloses the interior of the mitochondrion, which is known as the mitochondrial matrix. The inner membrane also forms a large number of folds, called cristae, that extend into the matrix. See Fig.
1. relative atomic mass - (chemistry) the mass of an atom of a chemical element expressed in atomic mass units. atomic mass, atomic weight. mass-the property of a body that causes it to have weight in a gravitational field.
Atomic weight: Definition: The average mass of the atoms of an element. This is a weighted average of the naturally-occurring isotopes. -Ratio of the average mass of a chemical element's atoms to some standard. Since 1961 the standard unit of atomic mass has been one-twelfth the mass of an atom of the isotope carbon-12.