Ions in the buffer solution conduct electricity. The DNA fragments are mixed with a small volume of loading dye. This dye is dissolved in a dense sugar solution, so that when it is added to the wells, it sinks to the bottom, taking the DNA with it. An electrical potential is applied across the gel. Phosphate groups give the DNA fragments a negative electrical charge, so that the DNA migrates through the gel towards the positive electrode.
Small fragments move quickly through the porous gel - larger fragments travel more slowly.
In this way the pieces of DNA are separated by size. The loading dye also moves through the gel, so that the progress of the electrophoresis can be seen. Other exhibits in this prestigious tour included Stephenson's Rocket, Hooke's microscope and a reconstruction of the original Watson and Crick DNA model. The Plant DNA Investigation kit developed by the NCBE with additional protocols from Science and Plants for Schools and the Plant Science Centre . We also supply a full range of replacement parts and consumables .