Gel Electrophoresis

Gel Electrophoresis

• Gel electrophoresis is a technique used to separate fragments of DNA.
• Separates fragments as a function of size.
• Most types use Agarose to separate fragments.

• Agarose is a porous gel. It can allow the passage of molecules through, however, larger molecules move more slowly through it since they cannot squeeze through the pores as easily as smaller molecules.

Gel electrophoresis apparatus

 

• Technique.

• An agarose gel is casted with several holes called wells at one end.
• The gel is placed in an electrophoresis box which is filled with an electrolyte buffer solution.
• Samples of digested DNA are placed in the wells
• Electrical leads are attached to the ends of the box creating an electrical potential across the apparatus.
  • Because DNA has a negative electrical charge. It is "pulled" towards the positive side of the apparatus.
  • Also, since the smaller molecules travel faster through the agarose. Over time this separates the various sized fragments of DNA.
• The gel is then removed and stained for DNA. This results in a gel which shows several bands of stained DNA.

Electrophoresis gel