So let's begin with step number one. Now, we know that inside our fluids of our body, we don't simply have a CO2 molecule dissolved because CO2 by itself is a very non polar molecule and so it cannot simply dissolve in our blood. And we have an enzyme called Carbonic and Hydrate that is basically used to transform the CO2 into bicarbonate ions. And this takes place in the cytoplasm of our red blood cells. And so we actually find bicarbonate ions dissolved in our cytoplasm and in our blood. And so in the first step, what we do is we essentially activate that bicarbonate molecule to form this carboxy phosphate intermediate.