So this carbon here and this carbon here, they have a different stereo chemistry. Now, why do we need this specific stereo chemistry? Why can't we use this? Well, because the enzyme in the second process of this pathway basically uses only this type of stereochemistry and not this type of stereo chemistry. So we need to form the zelulose as a result of this trans ketilase that we'll talk about in just a moment. So ultimately, in process one, we want to transform ribose phyphosphate into a zelulos phosphosphate.