Urea cycle

Organisms that cannot easily and quickly remove ammonia usually have to convert it to some other substance, like urea or uric acid, which are much less toxic.

The urea cycle consists of 5 reactions: 2 mitochondrial and 3 cytosolic. The urea cycle converts two amino groups to the relatively nontoxic excretion product urea at the cost of four "high-energy" phosphate bonds (3 ATP  and one AMP).