Mitochondria

Mitochondria (from the Greek. mitos - thread and chondrion - grain) - cellular organelles in the cytoplasm. In living cells are kind of small, highly refracting light grains (chondriosome) or threads (henkiokunta) up to 10 MK performing oscillatory or translational motion (possibly associated with the current protoplasm); they can fall into a number of small grains (chondroitin), share split. The combination of mitochondria of cells called chondriosome. Mitochondria are able vital painted Janus green, due to the presence of system of cytochrome C oxidase.
Mitochondria are very sensitive to osmotic environment changes, collapse at fixing cells. Best clips for M - osmaeva and chromic acid. Meters have characterized the ultrastructure (Fig). From protoplasm, they separated the outer mitochondrial membrane with smooth contours. Inner sheath M. forms a series of folds in the form of ridges (or Christ), directed in M the Number of Crist in mitochondria is variable, as is the scope of their location. Often, instead Krist inner sheath M forming processes in thin tubes. Between the shells visible light space width of 60-80+.
On ultrathin sections when observed in the electron microscope, each membrane M has the form of two dark layer thickness of about 15 And separated light layer. According to Robertson (J. Bobertson), dense layers are a series lipoproteidnyi molecules; Lestrange (F. S. Sjostrand), membrane M. built of globular structures that form a continuous layer. On the inner membrane M detect so-called elementary particles, located on the membrane surface, facing the inside mitochondria. Elementary particle with size up to 80 And consist of a base in the form of short cylinder and head. According to green (D. Green), it macromolecular complex, which the electron transfer. In addition, in M. there are matrix - amorphous dense substance, filling the space between Christ, in which detect DNA strand and often large (up to 700 A) granules of unknown nature.
Mitochondria change in different functional States of the cells. So, with the increase in the cells of the intensity of protein synthesis size and the number M increase. The appearance in the cytoplasm granules fat in starvation topographically associated with mg that swell the number Christ in them is reduced. In some cases, in M. there is an accumulation of proteins.

The mitochondria of the cells of the intestinal epithelium mouse: 1 - external membrane; 2 - the inner membrane; 3 - Krista. Arrows point to double the structure of mitochondrial membranes (upper Fig. - X 50 000; the lower figure. - X 150 000).

In pathologically changed cells there are various forms of modified M: fragmented, swollen with a reduced number Krist, with the disappeared matrix, with breaks of shells. With changes Meters are connected to the so-called cloudy swelling of cytoplasm and hyaline rebirth. When degeneration M can merge into a large body of chondriosome.
Concerning education M. there are two not yet fully proven capabilities: division by simply pressure.mania or fragmentation and re-education. In the latter case, mitochondria can occur through changes or microtiles (synonym of promothody; single bubbles with dense content), or membrane structures of cytoplasm.
Chemistry of mitochondria. Basic information about the chemistry M obtained in the study of isolated M. derived from mitochondrial fraction of homogenates (see) through further purification. M. consist of membranes and internal partitions (Crist) and unstructured content. The ratio of these elements and chemical composition of PM from various sources varies. Mitochondria obtained from the liver cells, contain 25-30% lipids, 65-70% of proteins, about 0.5% of RNA and minor amounts of DNA. Both nucleic acids (see) differ in nucleotide content from the relevant components of the other parts of the cell and, apparently, are involved in the biosynthesis of proteins, especially enzymes themselves Meters Important parts Meters are cytochromes and other oxidizing enzymes. M. contain all the necessary enzymes of tricarboxylic acid cycle and oxidative phosphorylation (see biological Oxidation). The basic biochemical function of mitochondria - the energy needed for vital functions of cells, by means of oxidation and oxidative phosphorylation. Released the energy is accumulated in the form of high energy phosphate bonds between the ATP. In mitochondria is also the biosynthesis of proteins, primarily oxidizing enzymes.
Careful fractionation M allows to single out the macromolecular complexes connected with an elementary act of electron transfer, separated from phosphorylation. M able to be reduced in the presence of ATP ions etc. To Other agents (thyroxine, phosphate) cause swelling of the Feet, leading to fragmentation of oxidative phosphorylation. Reversible swelling and reduction of mitochondria plays an important role in the regulation of metabolism of cells by selecting in the cytoplasm of the factors strengthening glycolysis, etc. Under pathological conditions (for example, in the cells of tumors) this ability is largely lost. Cm. also the Cell (chemistry cells).