In week 4, we learned about the process of agarose gel electrophoresis and how the technique can be used to separate the color components of common food dyes. Although gel electrophoresis is typically used to separate DNA or proteins, it essentially uses electricity to pull selective fragments of molecules across a gel and can be used to separate the components of any molecules by size.
We first went upstairs to the biochemistry lab to prepare the agarose gel. Agarose is one of the components of agar (the other one being agaropectin) and is extracted from seaweed. It is a polysaccaride polymer and comes as a white powder. When dissolved in hot water and cooled, it forms a gel that we can apply and run the samples through. After running a gel in which the all the colors bled into each other, we soon learned that we only had to apply very small amounts of the dyes to the wells of the gel.
A constant charge must be applied in order to get the fragments to move across the gel. We connected our gel to two electrodes, a negative anode and a positive cathode. We tested blue, yellow, red, green, orange, and purple food dyes. We found that all of these dyes were made up of blue, pink, orange, and yellow components. The yellow color components were made of the smallest fragments and travelled the farthest, while the blue color components were made of the largest fragments and traveled the least. Here is a photo of the gel after it was run: