Gel electrophoresis uses electricity, gelatin-like gel, macromolecules and a staining solution to measure and quantify the elements in a solution. Once your gel is made and solidifies, insert the solution you are testing into the lanes at the end of the gel. The electricity forces the DNA and RNA to go from the negative charge toward the positive charge. Protein can either have a net positive or net negative charge. Scientists began denaturing protein to give it a negative charge so it migrates through the gel in a similar fashion to DNA and RNA. Smaller molecules make it further along the gel than longer molecules because the molecules must work their way through the porous gel.
Bands are the proof that a molecule has separated into fragments based on the size of the fragment. The fragments, also called components, spread out over the length of the gel within their individual lane. This allows you to compare each solution next to one another. Bands that are equal distance from the start of the lane are going to be approximately the same size. For example, you can put an experimental DNA solution in one lane and a known DNA solution in another and compare the components at the end of the experiment.
Seeing how far the bands have moved along the gel indicates their size in relation to the other solutions in the gel. Gel electrophoresis can be used to determine the contents of an unknown solution compared to a known solution. The test also tells you if there are contaminants in the genetic material that are causing its components to behave outside of normal expectations. Take your gel type, agarose or polyacrylamide, into consideration when reading your results as DNA and RNA act differently in the two different gels. For example, circular forms of DNA migrate slower in agarose than linear forms.
Bands for genetic material are measured in base pairs. The more base pairs a molecule has, the longer it is and the slower it moves through the gel substance. You must run a standard DNA or RNA sample next to your experimental DNA sample to compare the lengths. When proteins are denatured, they migrate only based on their size and not on their charge or structure. You must compare similarly denatured proteins in your gels to yield accurate results.