Mitochondrion
A mitochondrion is a rod-shaped organelle present in plant and animal cells in which aerobic respiration takes place, releasing energy for metabolism 1. Bacterial cells have no mitochondria.
Function
glucose + oxygen ──► carbon dioxide + water + energy
(in the mitochondrion)The energy released is used for muscle contraction, protein synthesis, cell division, active transport, growth, the passage of nerve impulses and maintaining a constant body temperature 1.
Number and Distribution
| Cell type | Why many mitochondria |
|---|---|
| Muscle cell | Contraction demands a continuous energy supply |
| Sperm cell | Mitochondria release the energy for the flagellum to swim |
| Root hair cell | Active transport of mineral ions against a concentration gradient |
| Palisade mesophyll cell | Photosynthesis and its products need processing |
Cells with high energy demands contain many mitochondria, while less active cells contain few — an example of structure matching function.
Related
- Respiration - Reactions that occur inside the mitochondrion.
- Cell - Structural unit containing mitochondria.
- Cytoplasm - Material in which mitochondria are suspended.
- Movement - Contraction and swimming depend on respired energy.
- Biology - Cambridge IGCSE life-science area.
Footnotes
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Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028 - Mitochondria in cell structure (2.1.1-2.1.4), uses of energy (12.1), aerobic respiration (12.2), sperm adaptations (16.4). ↩ ↩2