Method of the Month — Gel Electrophoresis
August 2021
So, for the next few months, our Method of the Month features are going to be all about gel electrophoresis and the many variations on this simple technique. To start out this series, we’re giving an overview of the basics. If this intro article seems too simple to you, don’t worry, we’ll be able to add more complexity in future articles.
This is an ion.
Specifically, it’s a negatively charged one (an anion). By itself, it might not seem like much, but now imagine that you place this particle in some kind of electric field.
and it’s not hard to guess what happens next…
The positive electrode attracts the negative particle to itself. Ridiculously simple.
Well, this simple set-up is the basis for any electrophoresis experiment used in biology. Take a charged particle, put it in something that can conduct electricity (which is usually some kind of liquid buffer), then send an electrical current through it to make the particle (or particles) move.
So that’s the electrophoresis part, but what about the “gel” part. Well, if you want to actually be able to see your sample, you can’t just pipette into your liquid buffer. You need a solid medium that both holds your sample and allows movement. This is where gels come in.
In this technique, the gel is some sort of solid through which your sample particles can move. Often it’s made of a solution containing a sugar called agarose, which forms a microscopic meshwork when the solution solidifies. So now we have one additional piece of our gel electrophoresis set up.
This meshwork slows down the particles moving through it, which leads to the most important part of gel electrophoresis: separation.
Depending on things like size, shape, magnitude of charge, and interactions with the gel material, different kinds of particles will travel at different rates through the gel.
If you are really interested, there’s some cool mathematics and physics behind predicting how different particles will move depending on their characteristics. Here’s a link if you want to check that out.
Like many of the best techniques in biological research, there is a lot of versatility in this method, as you’ll see in the next few features. This simple set-up has applications in separating and analyzing DNA, RNA, and protein (the full central dogma). Check back next month for our next gel-based method!
