Gel electrophoresis

Using an enzyme called a restriction endonuclease, the DNA in a gene can be cut into fragments. Genes with mutation may give fragments of different sizes.

Gel elctrophoresis is a technique used to separate the DNA fragments based on their size. It is based on the premise that the different sized fragments will move through a special gel at a different rate when an electric current is applied.

Step one is to load the DNA sample in a hole or “well” at the top of the gel. In the first column or “lane”, we will place our DNA sample. In the second lane, we place a sample of DNA with fragments of known sizes to use a reference.
In step two, we apply the electric current and allow the fragments to move through the gel. The smaller fragments move more rapidly and are seen fruther down the lane.