So we have these proteins that vary in size, and we can use this property of size to basically separate and purify mixture of proteins. And one technique that we developed over the years to help us purify mixture of proteins based on size is gel filtration chromatography, also known as molecular exclusion chromatography. So let's begin by taking a look at the setup. The setup is relatively simple. We have this funnel, and we place the funnel on top of this long column. And inside the column, we have these gel beads.