Mitochondria (from the Greek. Μίτος - thread, χόνδρος - grain, seed) - it organelles cells involved in the processes of cellular respiration and store energy in the form of ATP molecules.It is in the form of ATP energy is made available for energy expenditure of the cell.
Mitochondria are found in almost all eukaryotic cells except red blood cells of mammals and some parasitic protozoa.The number of these organelles within the cell can be from a few, as in spermatozoa some protozoa and algae to many thousands.Particularly large number of mitochondria in cells, requiring large energy reserves.In animals, this muscle tissue, the liver cells.
Mitochondria are usually spherical, oval or rod-shaped, but in neurons, for example, they are in the form of threads, and some fungi is branched
giant "power station".
Despite the different forms, they all essentially similar to mitochondria, the structure of a single plan.Like plastids, the organelles are made up of two membranes: a smooth outer membrane and the inner is represented by numerous folds, baffles and protrusions.The folds of the inner membrane of mitochondria called Christie.They have a large total surface and that they take place the processes of cell oxidation.
As plastid in plant cells, mitochondria have their own genetic apparatus.Their DNA as prokaryotes ring represented chromosome.This suggests that the ancestors of mitochondria were free-living organisms, nuclear-free, which are then passed to a parasitic way of life, or entered into symbiosis with eukaryotes, and then did become an integral part of their cells.
addition to DNA, mitochondria have their own RNA and ribosomes.Before cell division, or spending it with intensive energy number of mitochondria as a result of their division increases to cover rising (or just coming) cell needs energy.If energy demand is low, the number of these organelles is reduced.
prokaryotes - organisms without nuclei is not having issued the nucleus separated from the cytoplasm by the nuclear envelope - karyoplasm.Their only circular chromosome located directly in the cell cytoplasm, and it is conventionally called "bacterial chromosome."From nuclear organisms - eukaryotes - prokaryotes there are many other fundamental differences.