So where does the cycle actually take place and why does it take place in the first place? So the urea cycle occurs predominantly in our hepatitis, in our liver cells, and to a smaller extent also takes place in our kidneys. So why does it actually take place? Well, the urea cycle gives us a way to transform a toxic byproduct of amino acid metabolism, namely ammonium, into less toxic form urea that can then be mobilized and transported to the kidneys, where the kidneys excrete the urea via urine. So that's what the urea cycle is. Now, let's take a look at the details of this cycle.