The mitochondria are organelles located with each cell. The mitochondria are bacillus shaped, or shaped like a drug capsule. In the fact that they are shaped like many common bacteria is not a coincidence. An important aspect of the mitochondria is called the endosymbiotic theory, or theory that the mitochondria arose from separate organisms that lived in symbiosis within the cells of host organisms. This is supported by the fact that mitochondria each have their own set of genes and DNA.
As contributing to cellular function, the most important aspect of mitochondria is the generation of cellular energy. All energy in all living things comes from the respiration of adenosine-tri-phosphate or ATP. Respiration involves the removal of a phosphate group from ATP resulting in adenosine-di- phosphate, or ADP. This ADP must be recycled in order to be used again. The name of the biochemical pathway responsible for regenerating ATP is called the Krebs cycle, after it’s discoverer. The Krebs cycle takes place in, or more specifically, on the membrane surrounding mitochondria. In brief, the goal of the Krebs cycle is to use energy from carbohydrate to turn ADP into ATP.
As I mentioned, mitochondria have their own DNA, which is separate from the cells chromosomal DNA in the cells nucleus. Perhaps most importantly, from a biotechnology standpoint, is that an individual receives chromosomal DNA from both of their parents. Alternatively, mitochondrial DNA comes only from the mother because mitochondria do not participate in the egg-sperm fertilization process. Mitochondria multiply by themselves within the cell. For this reason, if a biologist wants to compare the taxonomy of two different species, he does so using mitochondrial DNA or miDNA. If the sequence of two mitochondrial DNAs’ are similar, that is considered stronger evidence that the species are closely related than physical appearance.
Cells that use the most energy, such as heart muscle cells have many mitochondria. Likewise, one aspect of training, or regular exercise, is increasing the number of mitochondria in the cells of the tissues undergoing training, as well as the whole body. This is one contribution to the “training effect” that we observe in conjunction with exercise programs.
The number of mitochondria in cells naturally declines as we age. That is why, the AARP recommends exercise for its members as a means to keep healthy. A prospect supported not only by common observation, but exercise science research on the number and function of mitochondria in the cells of study subjects.
Read also: Mitochondria function
