Mitochondria Mitochondria are tiny organelles found in nearly all eukaryotic cells. They are rather large organelles ranging from 0.5µm to 10µm in length and 1µm in diameter. The mitochondria are the energy factories of the cell and are located in the cytoplasm. They are the sites of cellular respiration. The mitochondria are responsible for generating ATP from such organic fuels as simple sugars and fats in the process of cellular respiration. This doubled-membrane organelle has its own DNA and can reproduce by splitting itself. The mitochondria are sausage-shaped structures that move, change their shap