Where do the DNA migrate during electrophoresis?
I have never cared about the movement of the samples when I run agarose gel electrophoresis. Now, I do realize that it was a big mistake that I ever made!!! When I was put the gel on the wrong direction, I just stop the electrophoresis for a while and then turn the gel around to the opposite direction. Anyway, by that action I will loose more and more DNA. That is a big problem when I want to isolate the DNA from the gel! I always loose it. Yes, I saw the loading dye floating!! Oh, no! I will loose it again!
The negatively charged of phosphate groups of the nucleic acids confer an overall negative charge making the DNA migrate to the positive electrode (anode). However, it is not always happen if you use this kind of Mupid electrophoresis chamber (see the picture). There is a switch which can change the direction of DNA migration whenever you want or do not. Sometimes I use different switch on the chamber and put the gel in the same direction..so, certainly the DNA will migrate to the wrong way. Then, one thing that I have to do is to change the switch, not to turn the gel. It is still another mistake. I promise not to do the same mistake in the future or I will hate myself.
The switch position in the chamber is in the cathode (-) (Right side of the chamber). The DNA can migrate to this direction (see the picture) if you push the (+ –> – )switch button, so you have to be very carefully checking the switch position and put your gel or otherwise you will loose your samples!