Final answer:
Phosphorylation is the reverse of hydrolysis, adding a phosphate group to an organic molecule like ADP to form ATP, as seen in substrate-level phosphorylation during glycolysis.
Step-by-step explanation:
The reverse of hydrolysis is phosphorylation, which involves the addition of a phosphate group to an organic molecule. In biochemical processes, this often involves the formation of ATP from ADP and inorganic phosphate (Pi).
For example, during the glycolysis pathway, one reaction that illustrates this process involves 1,3-bisphosphoglycerate donating a phosphate group to ADP, resulting in the formation of ATP and 3-phosphoglycerate, a reaction catalyzed by phosphoglycerate kinase. This falls under the category of substrate-level phosphorylation.
The general reaction for phosphorylation can be represented as:
ADP + Pi + energy → ATP + H2O
In this reaction, energy is required to combine adenosine diphosphate (ADP) with inorganic phosphate (Pi) to form adenosine triphosphate (ATP), and water (H2O) is produced as a byproduct. This process is often coupled with other reactions within the cell to ensure efficient use of the energy provided.