mitochondrion

American  

[mahy-tuh-kon-dree-uhn] / ˌmaɪ təˈkɒn dri ən /

noun

Cell Biology.

1. the singular of mitochondria.

---

mitochondrion British  

/ ˌmaɪtəʊˈkɒndrɪən /

noun

1. Also called: chondriosome.  a small spherical or rodlike body, bounded by a double membrane, in the cytoplasm of most cells: contains enzymes responsible for energy production

---

mitochondrion Scientific  

/ mī′tə-kŏn′drē-ən /

plural

mitochondria

1. A structure in the cytoplasm of all cells except bacteria in which food molecules (sugars, fatty acids, and amino acids) are broken down in the presence of oxygen and converted to energy in the form of ATP. Mitochondria have an inner and outer membrane. The inner membrane has many twists and folds (called cristae), which increase the surface area available to proteins and their associative reactions. The inner membrane encloses a liquid containing DNA, RNA, small ribosomes, and solutes. The DNA in mitochondria is genetically distinct from that in the cell nucleus, and mitochondria can manufacture some of their own proteins independent of the rest of the cell. Each cell can contain thousands of mitochondria, which move about producing ATP in response to the cell's need for chemical energy. It is thought that mitochondria originated as separate, single-celled organisms that became so symbiotic with their hosts as to be indispensible. Mitochondrial DNA is thus considered a remnant of a past existence as a separate organism.

2. See more at cell cellular respiration

---

mitochondrion Cultural  

1. The cell organelle where much of cellular respiration takes place; the “power plant” of the cell.

---

Discover More

Mitochondria probably entered eukaryotes by an act of endosymbiosis, in which one simple cell was absorbed by another.

Mitochondria contain their own DNA. It is by tracing the mitochondrial DNA, which individuals inherit only from their mothers, that genetic linkages are often traced. (See mitochondrial Eve.)

Other Word Forms

• mitochondrial
  adjective

Etymology

Origin of mitochondrion

First recorded in 1900–05; see origin at mitochondria ( def. )

Explanation

A mitochondrion is the tiny part of a cell that generates energy for the entire cell. Your body contains an almost unbelievable number of mitochondria, an estimated ten million billion! Mitochondrion is the singular form of mitochondria, and it derives from Greek roots mitos, "thread," and khondrion, "tiny granule." This particular tiny granule is an organelle, a part of a cell with an extremely specialized function. In the case of a mitochondrion, its main job is taking in food and producing energy. Not every cell has mitochondria (red blood cells don't have any, for instance), but some cells contain thousands.

Example Sentences

"Each mitochondrion has many copies of mtDNA, which provides some backup protection. The repair systems for mtDNA are not as strong or efficient as those for nuclear DNA."

From Science Daily • Nov. 28, 2025

To try to fix this problem, the cell containing the faulty mitochondrion begins to export the excess nucleoids to its cellular trash bins.

From Science Daily • Mar. 1, 2024

Mitochondrial DNA is passed down from mother to child and can be found in hundreds of copies within each mitochondrion, which make it easier to recover and analyze.

From Scientific American • Aug. 25, 2023

The fat cells from the older, sedentary men showed relatively poor mitochondrial health, with fewer mitochondria than in the young men’s fat and less energy produced by each mitochondrion.

From Washington Post • Oct. 12, 2022

The cells in a drop of blood contain a different sort of molecular factory, the mitochondrion, which combines food with oxygen to extract useful energy.

From "Cosmos" by Carl Sagan