Mitochondria are organelles where cellular respiration functions take place in living things. In addition there are other cellular functions such as fatty acid metabolism, biosynthesis of pyrimidine, calcium homeostasis, cellular signal transduction and also as an energy producer.
The mitochondria is characterized by being large, compared to other cellular organelles, and having a globular shape. Its main function to supply the electron carriers (ATP) , product of cellular respiration, which provide the energy the cell needs.
Likewise, the mitochondria has the ability to reproduce on its own, this is because it has its own DNA, which allows it to form more mitochondria depending on the cell needs to have more ATP. So the more active the cells, the more mitochondria you will need.
The mitochondria obtain ATP when it performs cellular respiration, in this process it takes certain molecules from food in the form of carbohydrates that, when combined with oxygen, produce ATP.
How did mitochondria come about?
Mitochondria have biochemical and molecular characteristics similar to bacteria, such as the presence of circular DNA and ribosomes. For this reason, scientists believe that its origin is related to ancestral prokaryotic beings.
According to the Endosymbiotic Theory or Endosymbiogenesis , ancient prokaryotic organisms would have successfully hosted inside the eukaryotic cells of primitive organisms, evolving into the current mitochondria.
The same would have happened with chloroplasts , which resemble mitochondria due to the presence of a double membrane and its self-duplicating capacity.
See also : prokaryotic and eukaryotic cells
Curiosities
- The word mitochondria derives from the Greek, myths(line / thread) + chondros (granule / grain).
- Mitochondria are spherical or elongated and have dimensions of approximately 0.5 to 1 µm in diameter. They can represent up to 20% of the total cell volume.
- The DNA of mitochondria is exclusively maternal in origin.
- Mitochondria are also related to the process of cell death by apoptosis.
Mitochondria function
Below are the important functions that the mitochondria perform.
Energy production
The production of energy represented in ATP molecules is the most important function of the mitochondria. This energy is obtained through cellular respiration, a process that involves three stages in the mitochondria, being: the oxidation of pyruvate, the Krebs or citric acid cycle and oxidative phosphorylation.
Heat production
Heat production can be generated from exercise-associated thermogenesis, non-shivering thermogenesis, which occurs in the mitochondrial matrix, and diet-induced thermogenesis.
Apoptosis
It is the process of programmed and controlled cell death. Apoptosis is important in multicellular organisms since it controls the growth of cells, and for the development of organisms and tissues.
Calcium storage
Mitochondria serve to store calcium ions, which is very important for cellular biochemistry. Mitochondria regulate the amounts necessary for muscle contraction and the release of neurotransmitters, and it is of vital importance for bone health.
Sexual reproduction
Mitochondrial DNA is duplicated and its copies are transmitted through female gametes, that is, from the mother. Hence, some scientists consider that the mitochondria is part of the consequences of sexual preproduction.
Mitochondria structure
Mitochondria are formed by two lipoprotein membranes, one external and one internal:
- External membrane: similar to that of other organelles, smooth and composed of lipids and proteins called deporins, which control the entry of molecules, allowing the passage of relatively large ones.
- Internal membrane: it is less permeable and has numerous folds, called mitochondrial ridges.
The mitochondrial ridges protrude into the inner part of the mitochondria, a central space called the mitochondrial matrix, which is filled with a viscous substance containing respiratory enzymes that participate in the energy production process.
In the matrix are found ribosomes , organelles that produce proteins necessary for mitochondria. They are different from those found in the cell cytoplasm and more similar to that of bacteria. Another characteristic common to bacteria and mitochondria is the presence of circular DNA molecules.
