If the mitochondria are the "factories" of the cellular world, then adenosine triphosphate (ATP) is the chemical fuel that drives them. Adenosine triphosphate, the chemical energy currency of the plant and animal world, is required to for all the processes that keep organisms alive.

Energy is stored as a chemical bond between the endmost and central phosphate groups through a cycle that liberates adenosine diphosphate (ADP) and is released via enzyme action when needed. When an organism is resting, and energy is not such a limiting commodity, the reverse reaction takes place with the phosphate group being reattached to the ADP molecule utilizing energy derived from sunlight (in the case of photosynthesis) or from food (in cellular respiration). As with a series of batteries, ATP molecules act as chemical battery storage, storing rather than releasing reaction energy, at least until the organism requires it.

Adenosine triphosphate, a nucleotide, consists of a ribose (five-carbon sugar), a phosphate chain, and a purine base containing carbon and nitrogen atoms (adenine). In 1997, the Nobel Prize for Chemistry was shared by Dr. John Walker of Cambridge University, Dr. Paul Boyer from the University of California at Los Angeles (UCLA), and Danish scientist Dr. Jens Skou for their detailed description of the phosphorus cycle featured in the mitochondria of animal cells and the chloroplasts of plant cells. Life without adenosine triphosphate would not be possible, making it possibly the world's most important chemical substance.