So rapid simply means it takes place very quickly. And reversible means once we go this way, the enzyme also catalyzes that reverse reaction. In fact, once equilibrium is actually formed, this exists as the predominant molecule. In fact, 96% of the molecule is the DHAP and only 4% is the Gat. Now, why is that not a problem? Well, it's not a problem because biliciously as principle, once the gap is fed into stage three, it will be used up.