MITOCHONDRIAL MEMBRANE
Mitochondria are separated from the cytoplasm by an envelope consisting of two membranes, the inner and the outer one. Mitochondrial membranes are thinner than most of cell membranes; they are about 5 nm thick. There is the intermembranous space between the two membranes. The membranes differ from each other by ratio of proteins and lipids and chemical composition, which defines features of each membrane. The outer membrane contains many repeated molecules of transport protein forming wide hydrophilic channels in the double lipid layer. It resembles a sieve admitting all molecules of mass up to 10000 dalton, including small proteins. The outer membrane admits various ions, water, and sugars well. The inner membrane is impermeable for ions. That is why the chemical composition of the intermembranous space is equivalent to the composition of the cytosol at least in molecules of small size. The outer membrane of mitochondria is smooth; the inner one is very sinuous. The inner membrane is packed into cristae. The final stages of oxidation take place on the inner membrane. There is the electron transport chain and protein complex for ATP synthesis on the inner membrane. There is the matrix inside. It contains a concentrated solution of various enzymes.
|
Supplementary information
|