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Human Body Study

Mitochondria

The cell’s power plants — the organelles that convert fuel into usable energy. A cell may contain hundreds to thousands, more in energy-hungry tissues such as muscle.

Schematic of a generalized animal cell A labelled cross-section of a generalized animal cell. Each label links to the article for that part: the cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes and cytoskeleton. rough ER smooth ER Cell membrane Mitochondria Nucleus Endoplasmicreticulum Lysosomes Cytoskeleton Cytoplasm Ribosomes Golgi apparatus A generalized animal cell — schematic, not to scale. Not every cell contains every structure.

Structure

Section titled “Structure”

A bean-shaped organelle with two membranes; the inner one is deeply folded to maximize surface area. Mitochondria carry their own small loop of DNA, separate from the nucleus.

What it does

Section titled “What it does”
  • Energy production — completes the breakdown of fuel using oxygen, producing ATP, the molecule cells spend to do work.
  • Other roles — helps regulate the cell’s metabolism and can trigger programmed cell death.

Key idea

Section titled “Key idea”

Mitochondria are thought to descend from ancient free-living bacteria absorbed by early cells — which is why they keep their own DNA. They are also inherited only from the mother.