Mitochondria with Dr. Sohail Jamil Qureshi

Mitochondria (singular: mitochondrion)
are usually about 1 μm in diameter and can be various
shapes.
They are surrounded by two membranes (an envelope).
The inner of these is folded to form finger-like cristae which project
into the interior solution, or matrix. The space between the
two membranes is called the intermembrane space.
The outer membrane contains a transport protein called porin,
which forms wide aqueous channels allowing easy access
of small, water-soluble molecules from the surrounding
cytoplasm into the intermembrane space. The inner
membrane is a far more selective barrier and controls
precisely what ions and molecules can enter the matrix.