For example, the gel bead can be made from a sugar polymer cellulose, and we can add special side groups onto the cellulose that make them negatively charged, as shown in the following diagram. So this is a single bead that is found inside this column here. So the setup in inexchange chromatography consists of a funnel placed on top of a narrow column. The column is packed with these charge gel beads. And depending on the proteins that we actually want to separate, we can make those beads either positively charged, as in this case, or negatively charged, as in this particular case. So red means positively charged, and blue means negatively charged.