Synthesis of the compound adenosine triphosphate, or ATP, occurs on the inner membranes of bacterial cells and on the mitochondria and chloroplasts of plant and animal cells. The mitochondria and chloroplasts are structures inside plant and animal cells that are surrounded by a membrane.
ATP synthase is an enzyme that is used to make a compound for the cell that is rich in energy. ATP is often referred to as the "energy currency of life." The protein machines that are powered by ATP perform a number of different functions, such as:
- the manufacture of RNA, DNA and protein
- cleaning up cellular waste and debris
- moving chemicals out of, into and within cells
The miniscule size of the membranes on which the synthesis occurs dictates that molecules must be manipulated one at a time during the process. ATP is manufactured from two other chemicals, adenosine diphospate, or ADP, and phosphate. The energy used to convert ATP into new ATP molecules comes in the form of a hydrogen ion gradient. A positively charged electric current is created when the hydrogen ions stream through the ATP molecules. Examples of the flow of this current is the movement in the chloroplasts, from the lumen to the chloroplasts or in the mitochondria from the inter-membrane space into the matrix.