Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Phosphate groups are chemical units consisting of phosphorus atoms bonded to oxygen atoms. In cellular processes, they can be transferred from one molecule (like ATP) to another (like proteins) as a means of adding energy or regulating activity.
ATP is a molecule responsible for storing and transferring energy within cells. It consists of adenine, ribose sugar, and three phosphate groups.
Adenosine Diphosphate (ADP): ADP is formed when one phosphate group is removed from ATP through hydrolysis. It can be converted back into ATP through cellular respiration.
Energy Coupling: Energy coupling refers to the transfer of energy from exergonic (energy-releasing) reactions, like ATP hydrolysis, to endergonic (energy-consuming) reactions, enabling cellular work.