Answer: Phosphorylation reactions involve the addition of a phosphate group to another molecule called ADP (adenosine diphosphate)
Explanation:
Phosphorylation can of two kinds:
I) Substrate-level Phosphorylation which occurs when ATP is produced from the phosphorylation of ADP coupled to the loss of hydrogen atoms from an organic substrate
II) Oxidative Phosphorylation occurs when ATP is produced from the phosphorylation of ADP by using proton pump fuelled by the electron transport system.
Note that the difference between both (I and II) is that the former occurs independent of the electron transport system, UNLIKE the latter.
