Question

Why is it important to remove all the contents of your tubes before attempting to load a gel?

Answer 1

Because a change in DNA sequence will generation a slight change in charge which will effect the migration rate in electrophoresis.

Electrophoresis is basically the movement of particles in a fluid under the influence of a constant electrical field. Where positive or negative particles will move towards their counter electrodes.

The addition of a porous medium (a gel) for the separation will function as a retarding or sieving agent. This will slow down the movement or "migration" speed of larger molecules and/or less charged molecules.

That way, molecules of the different sizes will migrate on different rates. And molecules of the same size but with different charges, will migrate on different rates as well.

After a certain period of time, the electrical field is stopped and the gel is removed from the liquid for staining. After staining, the migrating molecules will form "bands" like in this picture below.

Answer 2

Answer:

Simply put, gel electrophoresis uses positive and negative charges to separate ... attempt to begin the procedure until you have studied them. ... Make sure you have all of your materials (listed above)