Page "Gel electrophoresis" Paragraph 6

If several samples have been loaded into adjacent wells in the gel, they will run parallel in individual lanes.

Depending on the number of different molecules, each lane shows separation of the components from the original mixture as one or more distinct bands, one band per component.

Incomplete separation of the components can lead to overlapping bands, or to indistinguishable smears representing multiple unresolved components.

Bands in different lanes that end up at the same distance from the top contain molecules that passed through the gel with the same speed, which usually means they are approximately the same size.

There are molecular weight size markers available that contain a mixture of molecules of known sizes.

If such a marker was run on one lane in the gel parallel to the unknown samples, the bands observed can be compared to those of the unknown in order to determine their size.

The distance a band travels is approximately inversely proportional to the logarithm of the size of the molecule.