mitochondrion
Americannoun
noun
plural
mitochondria-
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.
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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; mitochondria ( def. )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The compound is designed to block the damaging protein interaction and help mitochondria recover their normal function.
From Science Daily
The study, published in the Proceedings of the National Academy of Sciences, points to malfunctioning mitochondria as a major contributor to the progressive breakdown of cerebellar neurons known as Purkinje cells.
From Science Daily
Scientists have developed experimental compounds that prompt the mitochondria inside cells to use more energy and burn additional calories.
From Science Daily
A major focus of this effort is the mitochondria, often called the powerhouse of the cell.
From Science Daily
The evidence suggests that structures such as the nucleus emerged well before mitochondria.
From Science Daily
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.