Cell Organelles
Mitochondria:
The site of oxidative cellular respiration in eukaryotes; bacteria like organelle found within the cells of all but one species of eukaryotes. Mitochondria contain the enzymes that catalyze the citric acid cycle, which generates electrons that drive proton pumps within the mitochondrial membrane, and so fosters the chemiosmotic synthesis of ATP. Almost all of the ATP of nonphotosynthetic eukaryotic cells is produced in mitochondria.
A General Cell Overview