A report on Mitochondrion and Mitochondrial DNA

Two mitochondria from mammalian lung tissue displaying their matrix and membranes as shown by electron microscopy
Mitochondrial DNA is the small circular chromosome found inside mitochondria. These organelles, found in all eukaryotic cells, are the powerhouse of the cell. The mitochondria, and thus mitochondrial DNA, are passed exclusively from mother to offspring through the egg cell.
Simplified structure of a mitochondrion.
Electron microscopy reveals mitochondrial DNA in discrete foci. Bars: 200 nm. (A) Cytoplasmic section after immunogold labelling with anti-DNA; gold particles marking mtDNA are found near the mitochondrial membrane (black dots in upper right). (B) Whole mount view of cytoplasm after extraction with CSK buffer and immunogold labelling with anti-DNA; mtDNA (marked by gold particles) resists extraction. From Iborra et al., 2004.
Cross-sectional image of cristae in a rat liver mitochondrion to demonstrate the likely 3D structure and relationship to the inner membrane
Human mitochondrial DNA with the 37 genes on their respective H- and L-strands.
Electron transport chain in the mitochondrial intermembrane space
Human mitochondrial DNA with groups of protein-, rRNA- and tRNA-encoding genes.
Transmission electron micrograph of a chondrocyte, stained for calcium, showing its nucleus (N) and mitochondria (M).
The involvement of mitochondrial DNA in several human diseases.
Typical mitochondrial network (green) in two human cells (HeLa cells)
Animal species mtDNA base composition was retrieved from the MitoAge database and compared to their maximum life span from AnAge database.
Model of the yeast multimeric tethering complex, ERMES
Evolution of MROs
The circular 16,569 bp human mitochondrial genome encoding 37 genes, i.e., 28 on the H-strand and 9 on the L-strand.

Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP).

- Mitochondrial DNA

Although most of a cell's DNA is contained in the cell nucleus, the mitochondrion has its own genome ("mitogenome") that is substantially similar to bacterial genomes.

- Mitochondrion
Two mitochondria from mammalian lung tissue displaying their matrix and membranes as shown by electron microscopy

12 related topics with Alpha

Overall
Micrograph showing ragged red fibers, a finding seen in various types of mitochondrial diseases. Muscle biopsy. Gomori trichrome stain.

Mitochondrial disease

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Group of disorders caused by mitochondrial dysfunction.

Group of disorders caused by mitochondrial dysfunction.

Micrograph showing ragged red fibers, a finding seen in various types of mitochondrial diseases. Muscle biopsy. Gomori trichrome stain.
Example of a pedigree for a genetic trait inherited by mitochondrial DNA in animals and humans. Offspring of the males with the trait don't inherit the trait. Offspring of the females with the trait always inherit the trait (independently from their own gender).

Mitochondria are the organelles that generate energy for the cell and are found in every cell of the human body except red blood cells.

Mitochondrial disorders may be caused by mutations (acquired or inherited), in mitochondrial DNA (mtDNA), or in nuclear genes that code for mitochondrial components.

Eukaryote

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Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.

Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.

The endomembrane system and its components
Simplified structure of a mitochondrion
Longitudinal section through the flagellum of Chlamydomonas reinhardtii
Structure of a typical animal cell
Structure of a typical plant cell
Fungal Hyphae cells: 1 – hyphal wall, 2 – septum, 3 – mitochondrion, 4 – vacuole, 5 – ergosterol crystal, 6 – ribosome, 7 – nucleus, 8 – endoplasmic reticulum, 9 – lipid body, 10 – plasma membrane, 11 – spitzenkörper, 12 – Golgi apparatus
This diagram illustrates the twofold cost of sex. If each individual were to contribute the same number of offspring (two), (a) the sexual population remains the same size each generation, where the (b) asexual population doubles in size each generation.
Phylogenetic and symbiogenetic tree of living organisms, showing a view of the origins of eukaryotes and prokaryotes
One hypothesis of eukaryotic relationships – the Opisthokonta group includes both animals (Metazoa) and fungi, plants (Plantae) are placed in Archaeplastida.
A pie chart of described eukaryote species (except for Excavata), together with a tree showing possible relationships between the groups
The three-domains tree and the Eocyte hypothesis
Phylogenetic tree showing a possible relationship between the eukaryotes and other forms of life; eukaryotes are colored red, archaea green and bacteria blue
Eocyte tree.
Diagram of the origin of life with the Eukaryotes appearing early, not derived from Prokaryotes, as proposed by Richard Egel in 2012. This view implies that the UCA was relatively large and complex.

Eukaryotic cells typically contain other membrane-bound organelles such as mitochondria and Golgi apparatus; and chloroplasts can be found in plants and algae.

Mitochondria contain their own DNA, which has close structural similarities to bacterial DNA, and which encodes rRNA and tRNA genes that produce RNA which is closer in structure to bacterial RNA than to eukaryote RNA.

There is a wide variety of mitochondrial DNA genotypes in the maternal pool, which is represented by the bottle. The two genotypes in this maternal pool are represented by blue and yellow. When generated, each oocyte receives a small subsampling of mitochondrial DNA molecules in differing proportions. This is represented by the conveyor belt with oocytes, each one unique, as they are produced.

Heteroplasmy

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There is a wide variety of mitochondrial DNA genotypes in the maternal pool, which is represented by the bottle. The two genotypes in this maternal pool are represented by blue and yellow. When generated, each oocyte receives a small subsampling of mitochondrial DNA molecules in differing proportions. This is represented by the conveyor belt with oocytes, each one unique, as they are produced.
Sequence illustrating heteroplasmy genotype of 16169 C/T in Nicholas II of Russia.

Heteroplasmy is the presence of more than one type of organellar genome (mitochondrial DNA or plastid DNA) within a cell or individual.

In animals, mitochondria are the only organelles that contain their own genomes, so these organisms will only have mitochondrial heteroplasmy.

The structure of the DNA double helix. The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.

DNA

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Polymer composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.

Polymer composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.

The structure of the DNA double helix. The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.
Chemical structure of DNA; hydrogen bonds shown as dotted lines. Each end of the double helix has an exposed 5' phosphate on one strand and an exposed 3' hydroxyl group (—OH) on the other.
A section of DNA. The bases lie horizontally between the two spiraling strands ([[:File:DNA orbit animated.gif|animated version]]).
DNA major and minor grooves. The latter is a binding site for the Hoechst stain dye 33258.
From left to right, the structures of A, B and Z DNA
DNA quadruplex formed by telomere repeats. The looped conformation of the DNA backbone is very different from the typical DNA helix. The green spheres in the center represent potassium ions.
A covalent adduct between a metabolically activated form of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA
Location of eukaryote nuclear DNA within the chromosomes
T7 RNA polymerase (blue) producing an mRNA (green) from a DNA template (orange)
DNA replication: The double helix is unwound by a helicase and topo­iso­merase. Next, one DNA polymerase produces the leading strand copy. Another DNA polymerase binds to the lagging strand. This enzyme makes discontinuous segments (called Okazaki fragments) before DNA ligase joins them together.
Interaction of DNA (in orange) with histones (in blue). These proteins' basic amino acids bind to the acidic phosphate groups on DNA.
The lambda repressor helix-turn-helix transcription factor bound to its DNA target
The restriction enzyme EcoRV (green) in a complex with its substrate DNA
Recombination involves the breaking and rejoining of two chromosomes (M and F) to produce two rearranged chromosomes (C1 and C2).
The DNA structure at left (schematic shown) will self-assemble into the structure visualized by atomic force microscopy at right. DNA nanotechnology is the field that seeks to design nanoscale structures using the molecular recognition properties of DNA molecules.
Maclyn McCarty (left) shakes hands with Francis Crick and James Watson, co-originators of the double-helix model.
Pencil sketch of the DNA double helix by Francis Crick in 1953
A blue plaque outside The Eagle pub commemorating Crick and Watson
Impure DNA extracted from an orange

Eukaryotic organisms (animals, plants, fungi and protists) store most of their DNA inside the cell nucleus as nuclear DNA, and some in the mitochondria as mitochondrial DNA or in chloroplasts as chloroplast DNA.

"ragged red fibers" in MERRF syndrome

MERRF syndrome

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Mitochondrial disease.

Mitochondrial disease.

"ragged red fibers" in MERRF syndrome
Mitochondrial inheritance

The causes of MERRF syndrome are difficult to determine, but because it is a mitochondrial disorder, it can be caused by the mutation of nuclear DNA or mitochondrial DNA.

The cause of MERRF disorder is due to mutations in the mitochondrial genome.

HeLa cells stained for nuclear DNA with the blue fluorescent Hoechst dye. The central and rightmost cell are in interphase, thus their entire nuclei are labeled. On the left, a cell is going through mitosis and its DNA has condensed.

Cell nucleus

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In cell biology, the nucleus (pl.

In cell biology, the nucleus (pl.

HeLa cells stained for nuclear DNA with the blue fluorescent Hoechst dye. The central and rightmost cell are in interphase, thus their entire nuclei are labeled. On the left, a cell is going through mitosis and its DNA has condensed.
Diagram of the nucleus showing the ribosome-studded outer nuclear membrane, nuclear pores, DNA (complexed as chromatin), and the nucleolus.
A cross section of a nuclear pore on the surface of the nuclear envelope (1). Other diagram labels show (2) the outer ring, (3) spokes, (4) basket, and (5) filaments.
A mouse fibroblast nucleus in which DNA is stained blue. The distinct chromosome territories of chromosome 2 (red) and chromosome 9 (green) are stained with fluorescent in situ hybridization.
An electron micrograph of a cell nucleus, showing the darkly stained nucleolus
A generic transcription factory during transcription, highlighting the possibility of transcribing more than one gene at a time. The diagram includes 8 RNA polymerases however the number can vary depending on cell type. The image also includes transcription factors and a porous, protein core.
Macromolecules, such as RNA and proteins, are actively transported across the nuclear membrane in a process called the Ran-GTP nuclear transport cycle.
An image of a newt lung cell stained with fluorescent dyes during metaphase. The mitotic spindle can be seen, stained green, attached to the two sets of chromosomes, stained light blue. All chromosomes but one are already at the metaphase plate.
Human red blood cells, like those of other mammals, lack nuclei. This occurs as a normal part of the cells' development.
Oldest known depiction of cells and their nuclei by Antonie van Leeuwenhoek, 1719
Drawing of a Chironomus salivary gland cell published by Walther Flemming in 1882. The nucleus contains polytene chromosomes.

The cell nucleus contains all of the cell's genome, except for the small amount of mitochondrial DNA and, in plant cells, plastid DNA.

A small fraction of the cell's genes are located instead in the mitochondria.

Basal ganglia calcification, cerebellar atrophy, increased lactate; a CT image of a person diagnosed with MELAS

MELAS syndrome

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One of the family of mitochondrial diseases, which also include MERRF syndrome, and Leber's hereditary optic neuropathy.

One of the family of mitochondrial diseases, which also include MERRF syndrome, and Leber's hereditary optic neuropathy.

Basal ganglia calcification, cerebellar atrophy, increased lactate; a CT image of a person diagnosed with MELAS
Muscle biopsy of a person diagnosed with MELAS but carrying no known mutation. (a) Modified Gomori trichrome stain showing several ragged red fibers (arrowhead). (b) Cytochrome c oxidase stain showing Type-1 lightly stained and Type II fibers, darker fibers, and a few fibers with abnormal collections of mitochondria (arrowhead). Note cytochrome c oxidase negative fibers as usually seen in mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS). (c) Succinate dehydrogenase staining showing a few ragged blue fibers and intense staining in the mitochondria of the blood vessels (arrow). (d) Electron microscopy showing abnormal collection of mitochondria with paracrystalline inclusions (arrowhead), osmiophilic inclusions (large arrowhead) and mitochondrial vacuoles (small arrowhead).

A feature of these diseases is that they are caused by defects in the mitochondrial genome which is inherited purely from the female parent.

MELAS is mostly caused by mutations in the genes in mitochondrial DNA, but it can also be caused by mutations in the nuclear DNA.

The 16,569 bp long human mitochondrial genome with the protein-coding (red, orange, yellow), ribosomal RNA (blue), and transfer RNA genes (white). Non-coding mtDNA control region in grey.

Human mitochondrial genetics

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The 16,569 bp long human mitochondrial genome with the protein-coding (red, orange, yellow), ribosomal RNA (blue), and transfer RNA genes (white). Non-coding mtDNA control region in grey.
Mitochondrial inheritance patterns
The reason for maternal inheritance in mitochondrial DNA is that when the sperm enters the egg cell, it discards its middle part, which contains its mitochondria, so that only its head with the nucleus penetrates the egg cell.

Human mitochondrial genetics is the study of the genetics of human mitochondrial DNA (the DNA contained in human mitochondria).

Internal symbiont: mitochondrion has a matrix and membranes, like a free-living alphaproteobacterial cell, from which it may derive.

Symbiogenesis

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Leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms.

Leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms.

Internal symbiont: mitochondrion has a matrix and membranes, like a free-living alphaproteobacterial cell, from which it may derive.
Konstantin Mereschkowski's 1905 tree-of-life diagram, showing the origin of complex life-forms by two episodes of symbiogenesis, the incorporation of symbiotic bacteria to form successively nuclei and chloroplasts.
One model for the origin of mitochondria and plastids
Modern endosymbiotic theory posits that simple life forms merged, forming cell organelles, like mitochondria.
Kwang Jeon's experiment: [I] Amoebae infected by x-bacteria [II] Many amoebae become sick and die [III] Survivors have x-bacteria living in their cytoplasm [IV] Antibiotics kill x-bacteria: host amoebae die as now dependent on x-bacteria.
Mitochondria of a mammal lung cell visualized using Transmission Electron Microscopy
Diagram of endomembrane system in eukaryotic cell
The human mitochondrial genome has retained genes encoding 2 rRNAs, 22 tRNAs, and 13 redox proteins.
Simplified chart showing the three main mergers of the endosymbiotic theory
The three main mergers of the endosymbiotic theory
An anaerobic eukaryote with no mitochondria, perhaps resembling the present-day Giardia duodenalis parasite (which has secondarily lost its mitochondria), could have engulfed an aerobic proteobacterium and become symbiotic with it, and aerobic.

The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) taken one inside the other in endosymbiosis.

The presence of DNA in mitochondria and proteins, derived from mtDNA, suggest that this organelle may have been a prokaryote prior to its integration into the proto-eukaryote.

Henneguya zschokkei

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Species of a myxosporean parasite of certain species of salmon of genus Oncorhynchus.

Species of a myxosporean parasite of certain species of salmon of genus Oncorhynchus.

Henneguya salminicola is the first and thus far only known multicellular animal that completely lacks a mitochondrial genome and typical mitochondria, meaning it does not use aerobic respiration to produce energy, but some other, yet unknown, way; it as such does not breathe oxygen.