Search results
Results From The WOW.Com Content Network
A mitochondrion (pl. mitochondria) is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. [2]
Mitochondria and plastids contain their own ribosomes; these are more similar to those of bacteria (70S) than those of eukaryotes. [74] Proteins created by mitochondria and chloroplasts use N-formylmethionine as the initiating amino acid, as do proteins created by bacteria but not proteins created by eukaryotic nuclear genes or archaea. [75] [76]
The hydrogen hypothesis is a model proposed by William F. Martin and Miklós Müller in 1998 that describes a possible way in which the mitochondrion arose as an endosymbiont within a prokaryotic host in the archaea, giving rise to a symbiotic association of two cells from which the first eukaryotic cell could have arisen (symbiogenesis).
The analogy of bodily organs to microscopic cellular substructures is obvious, as from even early works, authors of respective textbooks rarely elaborate on the distinction between the two. In the 1830s, Félix Dujardin refuted Ehrenberg theory which said that microorganisms have the same organs of multicellular animals, only minor.
Evidence suggests that mitochondria can also undergo fusion and exchange (in a form of crossover) genetic material among each other. Mitochondria sometimes form large matrices in which fusion, fission, and protein exchanges are constantly occurring. mtDNA shared among mitochondria (despite the fact that they can undergo fusion). [citation needed]
Mitochondrial matrix has a pH of about 7.8, which is higher than the pH of the intermembrane space of the mitochondria, which is around 7.0–7.4. [5] Mitochondrial DNA was discovered by Nash and Margit in 1963. One to many double stranded mainly circular DNA is present in mitochondrial matrix. Mitochondrial DNA is 1% of total DNA of a cell.
As a result, mitochondria, within such cells, demonstrate a non-uniform distribution, and can be strategically localized in regions with the greatest energy needs. [25] In order to support the substantial metabolic demands of neurovascular coupling, astrocytic endfeet are loaded and packed with elongated and branched mitochondria. [26]
2005 tree of life showing horizontal gene transfers between branches including (coloured lines) the symbiogenesis of plastids and mitochondria. "Horizontal gene transfer and how it has impacted the evolution of life is presented through a web connecting bifurcating branches that complicate, yet do not erase, the tree of life". [49