The mitochondrion (, plural mitochondria) is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms. Some cells in some multicellular organisms may, however, lack mitochondria (for example, mature mammalian red blood cells). A number of unicellular organisms, such as microsporidia, parabasalids, and diplomonads, have also reduced or transformed their mitochondria into other structures. To date, only one eukaryote, "Monocercomonoides", is known to have completely lost its mitochondria, and one multicellular organism, "Henneguya salminicola", is known to have retained mitochondrion-related organelles in association with a complete loss of their mitochondrial genome. The word mitochondrion comes from the Greek , , "thread", and , , "granule" or "grain-like".
Introduction
Mitochondrion
Mitochondrion | Introduction
It is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms. It is a semi autonomous double-membrane-bound organelle. It is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms. The mitochondrion is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms.
the mitochrondria is the powerhouse of the cell
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Yes.
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who was the first to discover it?
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Richard Altmann.
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what exactly is it?
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The first observations of intracellular structures that probably represented mitochondria were published in the 1840s. Richard Altmann, in 1890, established them as cell organelles and called them "bioblasts". The term "mitochondria" was coined by Carl Benda in 1898. Leonor Michaelis discovered that Janus green can be used as a supravital stain for mitochondria in 1900. In 1904, Friedrich Meves, made the first recorded observation of mitochondria in plants in cells of the white waterlily, "Nymphaea alba" and in 1908, along with Claudius Regaud, suggested that they contain proteins and lipids. Benjamin F. Kingsbury, in 1912, first related them with cell respiration, but almost exclusively based on morphological observations.
Mitochondrion | History of discovery and research
The first high-resolution electron micrographs appeared in 1952, replacing the Janus Green stains as the preferred way of visualizing the mitochondria. This led to a more detailed analysis of the structure of the mitochondria, including confirmation that they were surrounded by a membrane. It also showed a second membrane inside the mitochondria that folded up in ridges dividing up the inner chamber and that the size and shape of the mitochondria varied from cell to cell.
Mitochondrion | History of discovery and research
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 an archaeon (classified as an undoubted prokaryote at that time), giving rise to a symbiotic association of two cells from which the first eukaryotic cell could have arisen (symbiogenesis). According to the hydrogen hypothesis:
Hydrogen hypothesis | Introduction
The proto-mitochondrion is the hypothetical ancestral bacterial endosymbiont from which all mitochondria in eukaryotes are thought to descend.
Proto-mitochondrion | Introduction
(The more related two species are, the more mtDNA/RNA mutations will be the same in their mitochondrial genome). Using these techniques, it is estimated that the first mitochondria arose around 1.5 billion years ago. A generally accepted hypothesis is that mitochondria originated as an aerobic prokaryote in a symbiotic relationship within an anaerobic eukaryote.
Human mitochondrial genetics | Genetic code variants
A mitoplast is a mitochondrion that has been stripped of its outer membrane leaving the inner membrane intact.
Mitoplast | Introduction
A mitochondrion contains DNA, which is organized as several copies of a single, usually circular chromosome. This mitochondrial chromosome contains genes for redox proteins, such as those of the respiratory chain. The CoRR hypothesis proposes that this co-location is required for redox regulation. The mitochondrial genome codes for some RNAs of ribosomes, and the 22 tRNAs necessary for the translation of mRNAs into protein. The circular structure is also found in prokaryotes. The proto-mitochondrion was probably closely related to "Rickettsia". However, the exact relationship of the ancestor of mitochondria to the alphaproteobacteria and whether the mitochondrion was formed at the same time or after the nucleus, remains controversial.
Mitochondrion | Origin and evolution
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. It is rich in guanine and cytosine content. Mitochondria of mammals have 55s ribosomes.
Mitochondrial matrix | Introduction
The mitochondrion (, plural mitochondria) is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms. Some cells in some multicellular organisms may, however, lack mitochondria (for example, mature mammalian red blood cells). A number of unicellular organisms, such as microsporidia, parabasalids, and diplomonads, have also reduced or transformed their mitochondria into other structures. To date, only one eukaryote, "Monocercomonoides", is known to have completely lost its mitochondria, and one multicellular organism, "Henneguya salminicola", is known to have retained mitochondrion-related organelles in association with a complete loss of their mitochondrial genome. The word mitochondrion comes from the Greek , , "thread", and , , "granule" or "grain-like".
Mitochondrion | Introduction
Outside the outer membrane there are small (diameter: 60Å) particles named sub-units of Parson.
Mitochondrion | Outer membrane
He named the granules "bioblasts", and explained them as the elementary living units, having metabolic and genetic autonomy, in his 1890 book ""Die Elementarorganismen"" ("The Elementary Organism"). His explanation drew much skepticism and harsh criticism. Altmann's granules are now believed to be mitochondria.
Richard Altmann | Introduction
In humans, brown adipose tissue is present at birth and decreases with age.
Mitochondrion | Heat production
g., mitosomes and hydrogenosomes). By this, mitochondria, hydrogenosomes, mitosomes, and related organelles as found in some loricifera (e. g. "Spinoloricus") and myxozoa (e. g. "Henneguya zschokkei") are together classified as MROs, mitochondrion-related organelles.
Mitochondrion | Origin and evolution
A published human mitochondrial DNA sequence revealed 16,569 base pairs encoding 37 genes: 22 tRNA, 2 rRNA, and 13 peptide genes. The 13 mitochondrial peptides in humans are integrated into the inner mitochondrial membrane, along with proteins encoded by genes that reside in the host cell's nucleus.
Mitochondrion | Matrix
Monocercomonoides is a genus of flagellate Excavata belonging to the order Oxymonadida. It was established by Bernard V. Travis and was first described as those with "polymastiginid flagellates having three anterior flagella and a trailing one originating at a single basal granule located in front of the anteriorly positioned nucleus, and a more or less well-defined axostyle". It is the first eukaryotic genus to be found to completely lack mitochondria, and all hallmark proteins responsible for mitochondrial function. Data suggests that the absence of mitochondria is not an ancestral feature, but rather due to secondary loss. "Monocercomonoides "sp. was found to obtain energy through an enzymatic action of nutrients absorbed from the environment.
Monocercomonoides | Introduction
The Rickettsiales are widely believed to be the closest relatives to mitochondria. Based on the fact that the "Midichlorian" genes for the flagellum and for the cbb3 cytochrome oxidase were proven to be ancestral, the genes were inferred to have been present in the bacterium that established the symbiosis with the ancestor of the eukaryotic cell, which became the mitochondrion. Hence, sequencing the genome of "M. mitochondrii" allowed an improved reconstruction of the mitochondrion's hypothetical free-living ancestor: It was a motile bacterium able to survive in microaerophilic conditions. Both these characteristics may have played an important role in the beginning of the symbiosis between the eukaryotic cell and the mitochondrion.
Midichloria | "Midichloria" and the origin of mitochondria
The vertebrate mitochondrial code (translation table 2) is the genetic code found in the mitochondria of all vertebrata.
Vertebrate mitochondrial code | Introduction
Mitointeractome is a mitochondrial protein interactome database.
Mitointeractome | Introduction
And, together with Daniel Mazia, he was the first to isolate the mitotic apparatus and subject it to biochemical study. This work demonstrated conclusively the existence of the mitotic spindle and initiated the modern biochemical study of mitosis.
Katsuma Dan | Introduction
Mitochondrial DNA was discovered in the 1960s by Margit M. K. Nass and Sylvan Nass by electron microscopy as DNase-sensitive threads inside mitochondria, and by Ellen Haslbrunner, Hans Tuppy and Gottfried Schatz by biochemical assays on highly purified mitochondrial fractions.
Mitochondrial DNA | History
Clustered mitochondria (cluA/CLU1) homolog is a protein in humans that is encoded by the CLUH gene.
CLUH | Introduction
Mitochondria contain their own genome, an indication that they are derived from bacteria through endosymbiosis. However, the ancestral endosymbiont genome has lost most of its genes so that the mitochondrial genome (mitogenome) is one of the most reduced genomes across organisms. The human mitochondrial genome is a circular DNA molecule of about 16 kilobases. It encodes 37 genes: 13 for subunits of respiratory complexes I, III, IV and V, 22 for mitochondrial tRNA (for the 20 standard amino acids, plus an extra gene for leucine and serine), and 2 for rRNA. One mitochondrion can contain two to ten copies of its DNA.
Mitochondrion | Genome
A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins. The two membranes have different properties. Because of this double-membraned organization, there are five distinct parts to a mitochondrion. They are: Mitochondria stripped of their outer membrane are called mitoplasts.
Mitochondrion | Structure
The MBU is the home of several freely-accessible scientific web-resources: MitoMiner - a mitochondrial proteomics database that provides information on cellular localisation, function and species & tissue specific expression The Integrated Mitochondrial Protein Index (IMPI) - a list of all the genes and proteins that make up the mammalian mitochondrion
MRC Mitochondrial Biology Unit | Resources
The ability of these bacteria to conduct respiration in host cells that had relied on glycolysis and fermentation would have provided a considerable evolutionary advantage. This symbiotic relationship probably developed 1.7 to 2 billion years ago. A few groups of unicellular eukaryotes have only vestigial mitochondria or derived structures: the microsporidians, metamonads, and archamoebae. These groups appear as the most primitive eukaryotes on phylogenetic trees constructed using rRNA information, which once suggested that they appeared before the origin of mitochondria. However, this is now known to be an artifact of long-branch attraction—they are derived groups and retain genes or organelles derived from mitochondria (e.
Mitochondrion | Origin and evolution
The phylogenetic analyses of the few genes that are still encoded in the genomes of modern mitochondria suggest an alphaproteobacterial origin for this endosymbiont. Although the order "Rickettsiales" has been proposed as the alpha-proteobacterial sister-group of mitochondria, there is no definitive evidence as to from which alpha-proteobacterial group the proto-mitochondrion emerged. Martijn "et al". found mitochondria are a possible sister-group to the alphaproteobacteria.
Proto-mitochondrion | Phylogeny
When diagramed, the resulting structure looks like the letter D. The D-loop was first discovered in 1971 when researchers noticed that many DNA in the mitochondria they were examining under microscope contained a short segment that was tripled stranded.
D-loop replication | Introduction
The kinetoplast, after which the class is named, contains the mitochondrial genome and is a dense DNA-containing granule within the cell's single mitochondrion. The structure is made up of a network of concatenated circular DNA molecules and their related structural proteins along with DNA and RNA polymerases. The kinetoplast is found at the base of a cell's flagella and is associated to the flagellum basal body by a cytoskeletal structure.
Kinetoplastida | Mitochondrion and kinetoplast DNA
In the following years, the mechanism behind cellular respiration was further elaborated, although its link to the mitochondria was not known. The introduction of tissue fractionation by Albert Claude allowed mitochondria to be isolated from other cell fractions and biochemical analysis to be conducted on them alone. In 1946, he concluded that cytochrome oxidase and other enzymes responsible for the respiratory chain were isolated to the mitochondria. Eugene Kennedy and Albert Lehninger discovered in 1948 that mitochondria are the site of oxidative phosphorylation in eukaryotes. Over time, the fractionation method was further developed, improving the quality of the mitochondria isolated, and other elements of cell respiration were determined to occur in the mitochondria.
Mitochondrion | History of discovery and research
Toni Gabaldón and Martijn Huynen (2003) reconstructed the proteome (the entire set of proteins expressed by a genome) and corresponding metabolism of the proto-mitochondrion by comparing extant alpha-proteobacterial and eukaryotic genomes. They concluded that this organism was an aerobic alpha-proteobacterium catabolyzing lipids, glycerol and other compounds provided by the host. At least 630 gene families derived from this organism can still be found in the 9 eukaryotic genomes analyzed in the study.
Proto-mitochondrion | Metabolism
The gene "OMA1" encodes a metalloprotease, a founding member of a conserved family of membrane-embedded metallopeptidases in mitochondria. The human gene has 9 exons and locates at chromosome band 1p32.2-p32.1
OMA1 | Gene
It was later determined that the lateral border Kent was referring to was in fact the oral aperture of "Trimastix", which also contained a fourth flagella . Today, the morphology of "Trimastix" is better understood, including details not initially observed by Kent, such as Trimastix lacking a conventional mitochondrion. Current research indicates that despite there being no strong evidence that the organelle can produce ATP, there are many mitochondrial functions that it appears to have maintained .
Trimastix | History of Knowledge
Around this time, the first proto-mitochondrion was formed. A bacterial cell related to today's "Rickettsia", which had evolved to metabolize oxygen, entered a larger prokaryotic cell, which lacked that capability. Perhaps the large cell attempted to digest the smaller one but failed (possibly due to the evolution of prey defenses). The smaller cell may have tried to parasitize the larger one. In any case, the smaller cell survived inside the larger cell. Using oxygen, it metabolized the larger cell's waste products and derived more energy. Part of this excess energy was returned to the host. The smaller cell replicated inside the larger one.
History of Earth | Emergence of eukaryotes
Peptide deformylase, mitochondrial is an enzyme that in humans is encoded by the "PDF" gene.
PDF (gene) | Introduction
Lewis was among the first scientists to observe the dynamics of mitochondria in living cells. In 1915 Margaret and Warren Lewis published a comprehensive analysis of the shapes and movements of mitochondria in cultured cells. Lewis's pioneering time-lapse studies included observations of mitochondrial movement toward and away from the centrosome, mitochondrial fission, and mitochondrial fusion. In the same paper, Lewis presented perhaps the first descriptions of stress-induced mitochondrial fragmentation and mitophagy.
Margaret Reed Lewis | Cell biology
George Lucas, director of the 1999 film "", in which midi-chlorians were introduced, described them as "a loose depiction of mitochondria". The non-fictional bacteria genus "Midichloria" was later named after the midi-chlorians of "Star Wars".
Mitochondrion | In popular culture
The specific name honours the researchers who discovered the holotype.
Arenysuchus | Introduction
Between protein-coding regions, tRNAs are present. During transcription, the tRNAs acquire their characteristic L-shape that gets recognized and cleaved by specific enzymes. Mitochondrial tRNA genes have different sequences from the nuclear tRNAs but lookalikes of mitochondrial tRNAs have been found in the nuclear chromosomes with high sequence similarity.
Mitochondrion | Genome
Of note, the arthropod mitochondrial genetic code has undergone parallel evolution within a phylum, with some organisms uniquely translating AGG to lysine.
Mitochondrion | Alternative genetic code
The protein is thought to be localized to the cytoplasm, although this is uncertain. It has also been predicted to be a 3-pass transmembrane protein. Also, a mitochondrial sorting signal was identified at the beginning of one of the protein isoforms using MitoProt II (located at Met416 of the largest protein variant).
ARMH3 | Expression
The translocase of the outer membrane (TOM) is a complex of proteins found in the outer mitochondrial membrane of the mitochondria. It allows movement of proteins through this barrier and into the intermembrane space of the mitochondrion. Most of the proteins needed for mitochondrial function are encoded by the nucleus of the cell. The outer membrane of the mitochondrion is impermeable to large molecules greater than 5000 Daltons. The TOM works in conjunction with the translocase of the inner membrane (TIM) to translocate proteins into the mitochondrion. Many of the proteins in the TOM complex, such as TOMM22, were first identified in "Neurospora crassa" and "Saccharomyces cerevisiae".
Translocase of the outer membrane | Introduction
There are two hypotheses about the origin of mitochondria: endosymbiotic and autogenous. The endosymbiotic hypothesis suggests that mitochondria were originally prokaryotic cells, capable of implementing oxidative mechanisms that were not possible for eukaryotic cells; they became endosymbionts living inside the eukaryote. In the autogenous hypothesis, mitochondria were born by splitting off a portion of DNA from the nucleus of the eukaryotic cell at the time of divergence with the prokaryotes; this DNA portion would have been enclosed by membranes, which could not be crossed by proteins. Since mitochondria have many features in common with bacteria, the endosymbiotic hypothesis is more widely accepted.
Mitochondrion | Origin and evolution
The "Thraustochytrium" mitochondrial code (translation table 23) is a genetic code found in the mitochondria of labyrinthulid "Thraustochytrium aureum". The mitochondrial genome was sequenced by the Organelle Genome Megasequencing Program.
Thraustochytrium mitochondrial code | Introduction
NADH-coenzyme Q oxidoreductase, also known as "NADH dehydrogenase" or "complex I", is the first protein in the electron transport chain. Complex I is a giant enzyme with the mammalian complex I having 46 subunits and a molecular mass of about 1,000 kilodaltons (kDa). The structure is known in detail only from a bacterium; in most organisms the complex resembles a boot with a large "ball" poking out from the membrane into the mitochondrion. The genes that encode the individual proteins are contained in both the cell nucleus and the mitochondrial genome, as is the case for many enzymes present in the mitochondrion.
Oxidative phosphorylation | NADH-coenzyme Q oxidoreductase (complex I)
Although it lacks significant sequence identity with any known vertebrate proteins, it seems likely that it evolved from a DNA glycosylase.
HBx | Introduction
One of its arms is embedded in the inner membrane of the mitochondria, and the other is embedded in the organelle. The two arms are arranged in an L-shaped manner. The total molecular weight of the complex is 1MDa.
NDUFAF5 | Structure
Wallin was the first to experimentally investigate the origin of mitochondria, particularly in relation to their similarities with certain bacteria. His first paper in 1922 described the staining techniques for bacterial cells, and found that the techniques were equally good for staining mitochondria. He concluded that "bacteria and mitochondria have a similar chemical constitution". His subsequent paper (in the same year and same journal) further strengthened his assumptions. In addition, he observed in his study of blue green algae that chloroplasts are "bacteria or bacteria-like organisms that accepted the leisure of a symbiotic partnership in the struggle for existence". He made a summary conclusion that: Wallin was aware that he needed to culture mitochondria isolated from cell in an independent environment.
Ivan Wallin | Origin of mitochondria
Malpighian is an attribute to several anatomical structures discovered by, described by or attributed to Marcello Malpighi:
Malpighian | Introduction
For example, it has been suggested that the SAR11 clade of bacteria shares a relatively recent common ancestor with the mitochondria, while phylogenomic analyses indicate that mitochondria evolved from a proteobacteria lineage that is closely related to or a member of alphaproteobacteria. The ribosomes coded for by the mitochondrial DNA are similar to those from bacteria in size and structure. They closely resemble the bacterial 70S ribosome and not the 80S cytoplasmic ribosomes, which are coded for by nuclear DNA. The endosymbiotic relationship of mitochondria with their host cells was popularized by Lynn Margulis. The endosymbiotic hypothesis suggests that mitochondria descended from bacteria that somehow survived endocytosis by another cell, and became incorporated into the cytoplasm.
Mitochondrion | Origin and evolution
2".
The Hermetic Organ | Introduction
Like other members of this order, these organisms do not have classical mitochondria. As such, much of the research involving these microbes is aimed at investigating the evolution of mitochondria. One species is "Trimastix pyriformis".
Trimastix | Introduction
The scenedesmus obliquus mitochondrial code (translation table 22) is a genetic code found in the mitochondria of "Scenedesmus obliquus".
Scenedesmus obliquus mitochondrial code | Introduction
This is particularly noticeable on the peripheral rib, which is broader than the rest and traceable on the two whorls preceding the body whorl.
Mitromorpha hewitti | Description
(Thomas) Martin Embley is a Professor at Newcastle University who has made contributions to our understanding of the origin of eukaryotes and the evolution of organelles such as mitochondria, mitosomes and hydrogenosomes, that are found in parasitic protists.
Martin Embley | Introduction
Eukaryotic cells typically have mitochondrial DNA; however, mitochondria that lack their own DNA have been found in a marine parasitic dinoflagellate from the genus "Amoebophyra". This microorganism, "A. cerati", has functional mitochondria that lack a genome. In related species, the mitochondrial genome still has three genes, but in "A. cerati" only a single mitochondrial gene — the cytochrome c oxidase I gene ("cox1") — is found, and it has migrated to the genome of the nucleus.
Mitochondrion | Lack of mitochondrial DNA
They were discovered in 1980 by Novick and Schekman, of the Department of Biochemistry, University of California, Berkeley.
Berkeley body | Introduction
Thus the placenta develops from the chorion frondosum and the decidua basalis.
Chorion | Parts
The trematode mitochondrial code (translation table 21) is a genetic code found in the mitochondria of Trematoda.
Trematode mitochondrial code | Introduction
The origins of the endomembrane system and mitochondria are also unclear. The phagotrophic hypothesis proposes that eukaryotic-type membranes lacking a cell wall originated first, with the development of endocytosis, whereas mitochondria were acquired by ingestion as endosymbionts. The syntrophic hypothesis proposes that the proto-eukaryote relied on the proto-mitochondrion for food, and so ultimately grew to surround it. Here the membranes originated after the engulfment of the mitochondrion, in part thanks to mitochondrial genes (the hydrogen hypothesis is one particular version). In a study using genomes to construct supertrees, Pisani "et al." (2007) suggest that, along with evidence that there was never a mitochondrion-less eukaryote, eukaryotes evolved from a syntrophy between an archaea closely related to Thermoplasmatales and an α-proteobacterium, likely a symbiosis driven by sulfur or hydrogen.
Eukaryote | Endomembrane system and mitochondria
In the mutant strain, proteins entered mitochondria from the cytosol normally but then misfolded and aggregated. They named the protein encoded by the affected gene HSP60, Heat shock protein 60, because it has a mass of 60 kDa and is produced in larger quantity in response to heat. Hsp60 is found in an 850 kDa double ring assembly, each ring containing 7 copies of Hsp60. Such assemblies, known as chaperonins, also exist in other cellular compartments and are essential components, mediating protein folding under both heat shock and normal conditions. Since 1987, Horwich and his colleagues have been studying these molecules both in "vivo" and "in vitro", with particular emphasis on the Hsp60 homologue in "E.
Arthur L. Horwich | Research
The chorion is the outermost fetal membrane around the embryo in mammals, birds and reptiles (amniotes). It develops from an outer fold on the surface of the yolk sac, which lies outside the zona pellucida (in mammals), known as the vitelline membrane in other animals. In insects it is developed by the follicle cells while the egg is in the ovary.
Chorion | Introduction
With the protein size correction, this codon is now identified as the initiation codon.
ARMET | Introduction
Recent measurements of the molecular clock for mitochondrial DNA reported a value of 1 mutation every 7884 years dating back to the most recent common ancestor of humans and apes, which is consistent with estimates of mutation rates of autosomal DNA (10 per base per generation.
Mitochondrion | Population genetic studies
Later, part of the 1997 Nobel Prize in Chemistry was awarded to Paul D. Boyer and John E. Walker for their clarification of the working mechanism of ATP synthase.
Mitochondrion | NADH and FADH: the electron transport chain
As chromatoid body is significantly bigger than other known RNP granules it is seen even with light microscopy and was discovered already in 1876 by A. von Brunn.
Chromatoid body | Introduction
Mitochondria (and related structures) are found in all eukaryotes (except two—the Oxymonad "Monocercomonoides" and "Henneguya salminicola"). Although commonly depicted as bean-like structures they form a highly dynamic network in the majority of cells where they constantly undergo fission and fusion. The population of all the mitochondria of a given cell constitutes the chondriome. Mitochondria vary in number and location according to cell type. A single mitochondrion is often found in unicellular organisms. Conversely, the chondriome size of human liver cells is large, with about 1000–2000 mitochondria per cell, making up 1/5 of the cell volume. The mitochondrial content of otherwise similar cells can vary substantially in size and membrane potential, with differences arising from sources including uneven partitioning at cell divisions, leading to extrinsic differences in ATP levels and downstream cellular processes.
Mitochondrion | Organization and distribution
39S ribosomal protein L33, mitochondrial is a protein that in humans is encoded by the "MRPL33" gene.
MRPL33 | Introduction
His early experiment was a failure using tissue samples from guinea pig, dog, and human blood. However, he succeeded in obtaining a mitochondrial culture with liver of fetal and newborn rabbits. He reported his findings in 1924 with a remark that "mitochondria are, in reality, bacterial organisms, symbiotically combined with the tissues of higher organisms." He continued with prolific publications. The series of his papers titled "On the nature of mitochondria" reached nine in 1925. He gave a full description of his experiments and theories on mitochondria in his 1927 book "Symbionticism and the Origin of Species". Although he claimed that his experiments were performed with utmost care, critics rejected them on the grounds of possible contamination, and Wallin and his works were largely forgotten, until Lynn Margulis introduced a more complete endosymbiotic theory with better evidences in 1967.
Ivan Wallin | Origin of mitochondria
Its name is derived .
Hyoid bone | Introduction
39S ribosomal protein L30, mitochondrial is a protein that in humans is encoded by the "MRPL30" gene.
MRPL30 | Introduction
Mitochondrial genomes use alternate start codons more significantly (AUA and AUU in humans). Many such examples, with codons, systematic range, and citations, are given in the NCBI list of translation tables.
Start codon | Mitochondria
Crista is an internal compartment formed by the inner membrane of a mitochondrion. Crista may also refer to: In anatomy:
Crista (disambiguation) | Introduction
The first contribution of Roland Douce was the characterization of cardiolipin, the major lipid of the mitochondrial membrane of plants and animals, as phosphatidyl ethanolamine. He then considerably improved the methods of purification of chloroplasts and mitochondria, and obtained the first envelope preparations. He was the first to show that the chloroplast shell is the site of biosynthesis of galactolipids and in particular MGDG, monogalactosyldiacylglycerol. With his team, he will characterize the lipid and protein components of the envelope of the plastids. He will succeed in separating the inner and outer shells. This work will pave the way for a detailed analysis of the chloroplast, its envelopes and functions .
Roland Douce | Main discoveries
The mitochondrion and its genome is a remnant of the α-proteobacterial endosymbiont. The majority of the genes from the symbiont have been transferred to the nucleus. They make up most of the metabolic and energy-related pathways of the eukaryotic cell, while the information system is retained from archaea.
Eukaryote | Endomembrane system and mitochondria
Protein MTO1 homolog, mitochondrial is a protein that in humans is encoded by the "MTO1" gene.
MTO1 | Introduction
The outer mitochondrial membrane, which encloses the entire organelle, is 60 to 75 angstroms (Å) thick. It has a protein-to-phospholipid ratio similar to that of the cell membrane (about 1:1 by weight). It contains large numbers of integral membrane proteins called porins. A major trafficking protein is the pore-forming voltage-dependent anion channel (VDAC). The VDAC is the primary transporter of nucleotides, ions and metabolites between the cytosol and the intermembrane space. It is formed as a beta barrel that spans the outer membrane, similar to that in the gram-negative bacterial membrane. Larger proteins can enter the mitochondrion if a signaling sequence at their N-terminus binds to a large multisubunit protein called translocase in the outer membrane, which then actively moves them across the membrane.
Mitochondrion | Outer membrane
Mitoguardin 1 is a protein that in humans is encoded by the MIGA1 gene.
Mitoguardin 1 | Introduction
Conventional TEM has also some technical limitations in verifying mitochondrial division. Cryo-electron tomography was recently used to visualize mitochondrial division in frozen hydrated intact cells. It revealed that mitochondria divide by budding. An individual's mitochondrial genes are not inherited by the same mechanism as nuclear genes. Typically, the mitochondria are inherited from one parent only. In humans, when an egg cell is fertilized by a sperm, the egg nucleus and sperm nucleus each contribute equally to the genetic makeup of the zygote nucleus. In contrast, the mitochondria, and therefore the mitochondrial DNA, usually come from the egg only. The sperm's mitochondria enter the egg, but do not contribute genetic information to the embryo.
Mitochondrion | Replication and inheritance
Nearly all have mitochondria with tubular cristae.
Rhizaria | Introduction
It was first described by Leonardo da Vinci in his exploration of human anatomy.
Moderator band (heart) | Introduction
Ivan Emanuel Wallin (22 January 1883 – 6 March 1969) was an American biologist who made the first experimental works on endosymbiotic theory. Nicknamed the "Mitochondria Man", he claimed that mitochondria, which are cell organelles, were once independent bacteria, as supported by his comparative studies and culture of isolated mitochondria. From 1922, he published a series of papers titled "On the nature of mitochondria" in the "American Journal of Anatomy" which became the experimental foundations of his claims. He was the first person to specifically postulate that eukaryotic organelles originated from bacteria, and that symbiosis is a major force in creation of new species.
Ivan Wallin | Introduction
After each endosymbiosis began, the partners would have eliminated unproductive duplication of genetic functions by re-arranging their genomes, a process which sometimes involved transfer of genes between them. Another hypothesis proposes that mitochondria were originally sulfur- or hydrogen-metabolising endosymbionts, and became oxygen-consumers later. On the other hand, mitochondria might have been part of eukaryotes' original equipment. There is a debate about when eukaryotes first appeared: the presence of steranes in Australian shales may indicate that eukaryotes were present 2.7 Ga; however, an analysis in 2008 concluded that these chemicals infiltrated the rocks less than 2.2 Ga and prove nothing about the origins of eukaryotes.
Evolutionary history of life | Chromatin, nucleus, endomembrane system, and mitochondria
Gopinath Kartha (26 January 1927 – 18 June 1984) was a prominent crystallographer of Indian origin. In 1967, he determined the molecular structure of the enzyme ribonuclease. This was the first protein structure elucidated and published in the United States.
Gopinath Kartha | Introduction
James Hurley is a university professor known for his research into proteins. He won the 2014 Neurath Award from the Protein Society for a unique, recent contribution to basic science.
James H. Hurley | Introduction
Under certain conditions, protons can re-enter the mitochondrial matrix without contributing to ATP synthesis. This process is known as "proton leak" or mitochondrial uncoupling and is due to the facilitated diffusion of protons into the matrix. The process results in the unharnessed potential energy of the proton electrochemical gradient being released as heat. The process is mediated by a proton channel called thermogenin, or UCP1. Thermogenin is a 33 kDa protein first discovered in 1973. Thermogenin is primarily found in brown adipose tissue, or brown fat, and is responsible for non-shivering thermogenesis. Brown adipose tissue is found in mammals, and is at its highest levels in early life and in hibernating animals.
Mitochondrion | Heat production
In Gif-sur-Yvette, Bernard Dujon started to study a strange genetic phenomenon, linked to mitochondrial genetics, whose study was still in infancy. When crossing two haploid yeast species carrying different mitochondrial mutations, conferring the resistance to erythromycin or to chloramphenicol, allele segregation did not follow mendelian rules and recombinants appeared in mysterious proportions. At that time, no one had any idea of the genetic content of mitochondria, except that it contained DNA. Bernard Dujon was studying a particular mitochondrial locus, called "omega", that could be present as two different alleles, "omega+" or "omega-". Genetic crosses between yeast cells carrying different alleles led to highly distorted inheritance in the progeny, since almost all cells ended up carrying the "omega+" allele! In 1974, he proposed a model in which gene conversion of the "omega-" allele to "omega+" was achieved by homologous recombination, replacing one allele by the other, copying in the process the flanking erythromycin and chloramphenicol mutations.
Bernard Dujon | The early years : discovery of the first homing endonuclease
ATP-binding cassette sub-family B member 7, mitochondrial is a protein that in humans is encoded by the "ABCB7" gene.
ABCB7 | Introduction
The inner mitochondrial membrane contains proteins with three types of functions: It contains more than 151 different polypeptides, and has a very high protein-to-phospholipid ratio (more than 3:1 by weight, which is about 1 protein for 15 phospholipids). The inner membrane is home to around 1/5 of the total protein in a mitochondrion. Additionally, the inner membrane is rich in an unusual phospholipid, cardiolipin. This phospholipid was originally discovered in cow hearts in 1942, and is usually characteristic of mitochondrial and bacterial plasma membranes. Cardiolipin contains four fatty acids rather than two, and may help to make the inner membrane impermeable.
Mitochondrion | Inner membrane
19 (1914).
Cephalophore | Introduction
It is one of many organisms to have had its genome sequenced.
Tammar wallaby | Introduction
Schatz played a leading role in elucidating the biogenesis of mitochondria and in discovering mitochondrial DNA. He recognized that this DNA encoded only a small number of mitochondrial proteins which was decisive for his further research on the import of proteins into the mitochondria and the degradation of proteins within these organelles. Schatz discovered a complex transport system that recognizes mitochondrial proteins made in the cytoplasm by specific signals attached to these proteins and then transfers them into the mitochondria. This system comprises two protein complexes, TOM and TIM, which are localized in the outer and inner mitochondrial membranes respectively.
Gottfried Schatz | Work
Anthony William Linnane (1930–2017) was an Australian professor of biochemistry, known for his work on mitochondria.
Anthony William Linnane | Introduction
Nuclear mitotic apparatus protein 1 is a protein that in humans is encoded by the "NUMA1" gene.
Nuclear mitotic apparatus protein 1 | Introduction
Endosymbiotic theory for the origin of mitochondria suggests that the proto-eukaryote engulfed a protomitochondria, and this endosymbiont became an organelle.
Symbiogenesis | Endosymbiosis of Protomitochondria
39S ribosomal protein L23, mitochondrial is a protein that in humans is encoded by the "MRPL23" gene.
MRPL23 | Introduction
The genome of this organism's mitochondrion and plastid were first sequenced in 2018.
Prototheca zopfii | Genome
Megamitochondria is extremely large and abnormal shapes of mitochondria seen in hepatocytes in alcoholic liver disease and in nutritional deficiencies. It can be seen in conditions of hypertrophy in cell death.
Megamitochondria | Introduction
Mazia's research focused mainly on processes of mitosis , and was the first to isolate a spindle apparatus from a cell undergoing cell division. This research was done in conjunction with Katsuma Dan where they completed the first successful isolation of a mitotic apparatus from sea urchin eggs. This was a discovery that shocked the cell biology community. This discovery ended doubt of what the apparatus looked like, as well as opened a variety of new questions about the makeup of the apparatus, and how the appearance and disappearance of the structure was controlled. He never lost interest in the apparatus, and continued to research it throughout his career.
Daniel Mazia | Isolating the mitotic spindle
Not much is known about the function of HSP60. Mammalian HSP60 was first reported as a mitochondrial P1 protein. It was subsequently cloned and sequenced by Radhey Gupta and coworkers. The amino acid sequence showed a strong homology to GroEL. It was initially believed that HSP60 functioned only in the mitochondria and that there was no equivalent protein located in the cytoplasm. Recent discoveries have discredited this claim and have suggested that there is a recognizable difference between HSP60 in the mitochondria and in the cytoplasm. A similar protein structure exists in the chloroplast of certain plants. This protein presence provides evidence for the evolutionary relationship of the development of the mitochondria and the chloroplast by means of endosymbiosis.
HSP60 | Discovery
The chlorophycean mitochondrial code (translation table 16) is a genetic code found in the mitochondria of "Chlorophyceae".
Chlorophycean mitochondrial code | Introduction