The chemical composition of mitochondria mainly includes water, protein and lipids, and also contains a small amount of small molecules such as coenzyme and nucleic acid. Protein accounts for 65% ~ 70% of the dry weight of mitochondria. Protein in mitochondria is both soluble and insoluble.
Soluble proteins are mainly composed of enzymes located in mitochondrial matrix and membrane peripheral proteins; Insoluble protein constitutes most of the membrane, some of which are mosaic proteins and some are enzymes. Lipids in mitochondria are mainly distributed in two membranes, accounting for 20% ~ 30% of dry weight.
Phospholipids in mitochondria account for more than 3/4 of total lipids. The content of phospholipids in mitochondrial membranes of different tissues of the same organism is relatively stable. Rich in cardiolipin and less cholesterol are the obvious differences between mitochondria and other cell membrane structures in composition.
Mitochondria can be divided into four functional regions: outer mitochondrial membrane (OMM), space between mitochondrial membranes, inner mitochondrial membrane (IMM) and mitochondrial matrix. The outer membranes of mitochondria are parallel to each other and are typical unit membranes.
Among them, the outer membrane of mitochondria is smooth and acts as the boundary membrane of organelles; Mitochondrial intima folds inward to form mitochondrial crest, which undertakes more biochemical reactions. These two membranes divide mitochondria into two parts. The gap between the two membranes is the mitochondrial membrane, and the mitochondrial inner membrane is wrapped with the mitochondrial matrix.
Extended data
1, cells with mitochondria must be eukaryotic cells, which means that prokaryotic cells have no mitochondria, but some prokaryotic cells can use intracellular aerobic respiratory enzymes for aerobic respiration. Therefore, not all cells that can carry out aerobic respiration have mitochondria, and eukaryotic cells without mitochondria can only carry out anaerobic respiration, such as mature red blood cells and ascaris cells of mammals.
2. The main function of intracellular mitochondria is to provide energy for various life activities. As the main place for aerobic respiration, it is the "energy factory" of cells. About 95% of the total energy required for cell life activities comes from mitochondria, and the distribution of mitochondria in cells is related to the level of energy metabolism. However, mitochondria can not directly decompose glucose, but only pyruvate produced in cytoplasmic matrix.
3. From the "life experience" of mitochondria, we can further understand that mitochondria contain independent genetic materials and ribosomes, so they have the ability to synthesize protein independently, and are also controlled by nuclear genes in cells, so they are called "semi-autonomous organelles".
4. Mitochondrial structure: it has a double-layer membrane structure, and the inner membrane folds inward to form many folds, called "ridges", which provide more attachment sites for enzymes; It is a liquid matrix containing a small amount of DNA, RNA and various enzymes. Therefore, the enzymes in mitochondria are distributed on its matrix and intima.
Baidu encyclopedia-mitochondria