Respiration

Cellular respiration is an intracellular process in which glucose (C₆H₁₂O₆) is oxidized and the energy is used to make ATP (adenosine triphosphate). ATP is a high energy molecule which organisms use to drive energy-requiring processes such as biosynthesis, transport, growth, and movement. The general features of cellular respiration are the same in most organisms.

Cellular respiration consists of many separate enzymatic reactions. The entire process can be summarized in the chemical equation:

Cellular respiration is divided into three sequential series of reactions: glycolysis, the citric acid cycle, and the electron transport chain. In higher organisms (eukaryotes), glycolysis occurs in the cytosol of the cell, the aqueous region outside the nucleus; the citric acid cycle and electron transport chain occur in the mitochondria, cellular organelles (intracellular organ-like structures) which have characteristic double membranes and are specialized for ATP production.