This tutorial explores how biological macromolecules, such as proteins and nucleic acids, are separated according to size when direct current is applied to the ends of an agarose or polyacrylamide electrophoresis gel.

Use the mouse cursor to activate the Start button. This applies a virtual direct current (DC) voltage to the top and bottom portions of the electrophoresis gel plate, causing the macromolecule mixtures to migrate from one end of the gel to the other (in this tutorial, from the wells on the top to the bottom of the gel). Molecules in the left-most well (black) consist of a set of markers of known molecular weight that migrate as bands through the gel. In the second through sixth wells, unknown sets of macromolecules are placed (indicated by different colors), which will co-migrate as bands with the marker set. After the experiment is completed, the graph indicates the approximate molecular weight of the unknown macromolecules (indicated by the corresponding colored points on the graph). Plotted on the graph is the logarithm of the molecular weight versus the logarithm of the distance moved the each band of macromolecules in the gel.