In the case that a molecule is phosphorylated it means that it has an increased chemical reactivity and it is primed to do cellular work. Enzymes that are called kinases are responsible for phosphorylated molecules. They catalyze the transfer of phosphoryl on to organic molecules.
The source of this reaction in most cases is a molecule that is called adenosine triphosphate that is usually abbreviated as ATP. Adenosine triphosphate is a complex chemical that actually participates in many chemical processes involved with molecules. ATP is found in all forms of life and is sometimes referred to as the molecular unit of currency.