We explain what mitochondria are and the origin of these organelles. In addition, its main functions and how is its structure.
What are Mitochondria
Mitochondria are the cytoplasmic organelles (that is: cellular equivalents to the organs of the body) that in the cells operate as power plants, synthesizing the molecules adenosine triphosphate (ATP) that provide chemical fuel to the various cellular processes necessary for the life (cellular respiration).
This process of energy synthesis takes place inside the cell, taking advantage of glucose, fatty acids and amino acids as fuel, which enter the mitochondria through the membranes that cover them, similar although smaller in size to the cellular membrane.
Commonly, these organelles have an elongated appearance, although highly variable, and are found in the cell cytoplasm, in a number according to the energy needs of the type of cell in question.
The origin of mitochondria
The curious thing about mitochondria is that they have in their own DNA the necessary instructions to synthesize the substances essential energy resources and to replicate themselves during the cell reproduction. This DNA is not identical to that of the core of the cell, which has made it possible to formulate a hypothesis regarding its origin: endosymbiosis.
According to this theory, mitochondria would have arisen as a result of the symbiotic (collaborative) incorporation of a prokaryote within the eukaryotic cell, reaching a kind of coexistence agreement that later became indispensable: the prokaryote would produce energy for the entire cell and in return would be protected inside, a medium rich in nutrients and free from competition. The rest would be done by evolution, which would end up merging them both in the same organism.
The clues that support this theory have to do with the presence ofDNA autonomous and of a plasma membrane own in the mitochondria, as well as its physical, biochemical and metabolic similarity to numerous bacteria.
Function of the mitochondria
As has been said, the mitochondria are responsible for producing the chemical energy for the whole cell, from the synthesis of ATP. To do this, it must oxidize metabolites through oxidative phosphorylation, generating a very high percentage of the energy produced by the cell.
At the same time, the mitochondria serve as a store of ions, molecules Water Y protein, often captured from the cytoplasm to serve as spare parts in the synthesis of energy.
How is its structure?
The structure of the mitochondrion is variable, but it is generally made up of three different spaces: mitochondrial ridges, intermembrane space and mitochondrial matrix, all covered by a double lipid membrane, similar to the cell membrane, but composed mostly (60 to 70% in the external, 80% in the internal) of proteins.
- Mitochondrial ridges. It is a system of ridges or folds, which connects with the mitochondrial membranes from time to time, thus allowing the transport of materials into the organelle and exerting specific enzymatic (catalytic) functions.
- Intermembrane space. Between the two mitochondrial membranes there is a space rich in protons (H +) fruit of the enzymatic complexes of cellular respiration, as well as the molecules responsible for the transport of fatty acids into the mitochondria, where they will be oxidation.
- Mitochondrial matrix. Also called mitosol, it contains ions, metabolites to oxidize, double-stranded circular DNA molecules (very similar to bacterial DNA), ribosomes, RNA mitochondrial and everything necessary for the synthesis of ATP. There the Krebs cycle and the beta-oxidation of fatty acids take place, as well as reactions of synthesis of urea and heme groups, all of which generate a significant amount of chemical energy that is then released into the cell cytoplasm.