ISSA Nutritionist Practice Exam 2026 - Complete Preparation Guide

The process of adding a phosphate group to ADP to form ATP is known as phosphorylation. This reaction is crucial because it is how energy is stored in the body. When a phosphate is attached to ADP, it transforms into ATP, which serves as the primary energy currency in cells. Phosphorylation occurs during various metabolic pathways, such as through substrate-level phosphorylation during glycolysis or oxidative phosphorylation in the mitochondria.

Other processes include hydrolysis, which involves the breaking down of ATP into ADP and inorganic phosphate with the release of energy. Resphosphorylation refers to the specific reattachment of a phosphate group to ADP, but it is not as commonly defined in the same way as phosphorylation, which encompasses the broader action of adding a phosphate. Dephosphorylation, on the other hand, is the removal of a phosphate group, which decreases the energy storage. Thus, phosphorylation is the term used to specifically describe the addition of a phosphate group in the context of the ATP-ADP cycle.