In a eukaryote cell, chemiosmosis takes place in the mitochondria or chloroplasts. In prokaryotes, it takes place in the cell membrane. ATP, an energy source used by the cell to perform many of its functions, is produced in the process of chemiosmosis.
The chemiosmosis process occurs across a biological membrane. Specifically, it involves the movement of ions from an area of higher concentration to an area where they are lower in concentration. Chemiosmosis is possible through proteins in the cell known as transport proteins. The cell membrane is permeable to some ions and not others due to a proton gradient. Hydrogen ions travel across the cell membrane via the transport protein ATP synthase.