The organelle whose inner membrane is folded into structures called cristae
The folds vastly increase the surface area available for the electron transport chain.
Science · Biology
Mitochondrion
1898 (named by Carl Benda)
Biology — cell biology and bioenergetics
The mitochondrion is the double-membraned organelle in which eukaryotic cells carry out the citric acid cycle and oxidative phosphorylation, generating most of their ATP. It carries its own small circular genome and its own ribosomes, the strongest evidence for the endosymbiotic theory championed by Lynn Margulis: that it descends from a free-living alpha-proteobacterium engulfed by an ancestral cell. In humans it is inherited almost entirely down the maternal line, which makes it the basis of "Mitochondrial Eve" and of a class of maternally transmitted diseases.
How to spot them
- ▸Double membrane, the inner one folded into cristae
- ▸Has its own circular genome of 16,569 base pairs and 37 genes in humans
- ▸Inherited from the mother alone in almost all humans
- ▸Descended from a free-living bacterium, per the endosymbiotic theory
- ▸Popularly called the powerhouse of the cell
Key facts
Named in 1898 by Carl Benda, from the Greek for 'thread' and 'granule' (1898)
Earlier names included bioblast, coined by Richard Altmann in 1890.
The part of the human cell inherited only from the mother, giving rise to the idea of a single common female ancestor
'Mitochondrial Eve' is dated to roughly 150,000–200,000 years ago in Africa.
Lynn Margulis's 1967 paper 'On the Origin of Mitosing Cells' argued this structure was once a free-living bacterium (1967)
Published under her then-name Lynn Sagan and rejected by about fifteen journals first.
Has its own circular genome of 16,569 base pairs and 37 genes, and its own bacteria-like ribosomes
Its ribosomes are sensitive to antibacterial antibiotics, a clue to its bacterial ancestry.
The 'three-parent baby' technique replaces this structure's faulty DNA using a donor egg (2015)
The UK became the first country to legalise the donation technique.
Called 'the powerhouse of the cell' in a 1957 Scientific American article by Philip Siekevitz (1957)
The phrase became one of the best-known clichés in biology teaching.
Key ideas
- Peter Mitchell's chemiosmotic theory explains how it works: the electron transport chain pumps protons across the inner membrane, and the resulting gradient drives ATP synthase like water through a turbine.
- Because it retains only a fraction of its ancestral genome, most of its proteins are encoded in the nucleus and imported — a hallmark of endosymbiotic gene transfer.
Quick-fire facts
- •Named by the German pathologist Carl Benda in 1898, from Greek mitos (thread) and chondros (granule).
- •The endosymbiotic theory was revived and argued into the mainstream by Lynn Margulis from 1967; she has her own GoDeep entry as a scientist.
- •Peter Mitchell won the 1978 Nobel Prize in Chemistry for the chemiosmotic mechanism of ATP synthesis.
- •Paul Boyer and John Walker shared the 1997 Nobel Prize in Chemistry for the mechanism of ATP synthase.
- •The human version has 16,569 base pairs and 37 genes; the human nuclear genome has about 3.1 billion base pairs.
- •A human liver cell may contain 1,000–2,000 of them; a mature red blood cell has none at all.
- •Because it is inherited maternally and mutates relatively fast, its DNA is used to trace human migration and to identify remains, including those of the Romanovs.
- •The chemical it produces, ATP, is turned over so fast that a resting adult recycles roughly their own body weight in it each day.
- •Common misconception: it does not make energy. It transfers energy from food into the chemical bonds of ATP.
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Sources
- Bruce Alberts et al. — Molecular Biology of the Cell
- Nick Lane — Power, Sex, Suicide: Mitochondria and the Meaning of Life
- Lynn Sagan (Margulis) — On the Origin of Mitosing Cells (Journal of Theoretical Biology)