Biotech Basics: Agarose Gel Electrophoresis

Agarose gel electrophoresis is a biotechnology technique used to separate DNA molecules according to their size.  The mixture of molecules is added into depressions (or “wells”) within a gel, and then an electrical current is passed through the gel (Fig. 1A).  Because the sugar-phosphate backbone of DNA has a strong negative charge, the current drives the DNA through the gel towards the positive electrode (Fig 1B).


At first glance, an agarose gel appears to be a solid at room temperature. On the molecular level, the gel has small channels through which the DNA can pass. Small DNA fragments move through these holes easily, but large DNA fragments have a more difficult time squeezing through the tunnels. Because molecules with dissimilar sizes travel at different speeds, they become separated and form discrete “bands” within the gel. After the current is stopped, the bands can be visualized using a stain that sticks to DNA (Figure 1C).

While this technique is powerful enough to be used in the research lab, it is simple enough to be performed by middle- and high-school students. For many years, Edvotek has worked with teachers to make these experiments easy to perform in a classroom setting.  For example, we have streamlined our pre-lab preparations by providing the DNA samples as pre-aliquoted QuickStrips™. The agarose powder and electrophoresis buffer are also supplied in pre-measured quantities, meaning that you just need to dilute, dissolve and go!

Our electrophoresis equipment includes several great features to help make its use foolproof. Almost every person who has cast electrophoresis gels by taping the edges of the gel tray has had the molten agarose leak onto their lab bench. To get around this problem, we designed an innovative gel casting system to make gel preparation foolproof. In addition, we know that it’s easy to reverse the leads when setting up the electrophoresis chamber (especially if you are setting up an entire classroom!).  What makes our equipment stand out from the rest?

  1. We designed the electrophoresis chambers so that the gels and the lid can only be used in one direction, making it near impossible to reverse the current.
  2. we’ve color-coded the rubberized feet of the electrophoresis chamber.
  3. Large, color-coded push tabs makes lid removal simple.  
  4. Want to view the gel while it’s running? This can be difficult because the lid will fog up during electrophoresis. Our contoured lid and increased venting reduces condensation, making it easier to view the gel.  
  5. The power leads leave the lid at a 90° angle, conveniently tucking them out of the way.
  6. Removable, replaceable electrodes make it easy to repair the equipment in the comfort of your classroom.
  7. The molded pour spout helps with post lab cleanup – no more spilling electrophoresis buffer!

We think you’ll agree that these innovations will make electrophoresis experiments easy to perform.