Final answer:
Phosphorylation is the type of chemical reaction that occurs when a molecule gains a phosphate group. It involves attaching a phosphate to another molecule to facilitate a chemical reaction.
Step-by-step explanation:
The type of chemical reaction that occurs when a molecule gains a phosphate group is called phosphorylation. This is the process of attaching a phosphate to another molecule, which facilitates a chemical reaction.
A common example of phosphorylation is when adenosine diphosphate (ADP) gains a phosphate to become adenosine triphosphate (ATP), which is an important energy molecule in cells.