Gel Electrophoresis Lab

        Though there are natural alternatives, artificial food colors can be preferable to both consumers and manufacturers. They are much easier to mass-produce and obtain, and also include a wider range of bright colors (or colors that make food seem fresher) that can seem more appealing to consumers. Though I usually tend to avoid foods and snacks with dyes, I have seen sodas that contain different dyes, as well as chips (e.g. Doritos) that contain dyes like Yellow 5 and Yellow 6. Additionally, one large source of artificially dyed foods is dog food: manufacturers tend to add artificial food colors like Yellow 5, Blue 2, Red 40, and Yellow 6. This is likely to create a more “nutritious” appearance that may sway consumers.

        In our DNA electrophoresis lab, we ran dyes found in various common candies. We used the Red 40, Yellow 5, Yellow 6, and Blue 1 reference dyes to compare our dyes to. Observing the molecular structures of other dyes, we can see that they have similar structures to the four reference dyes we used, with analogous substituents (e.g. phenyl, hydroxyl, carbonyl); these similar structures would lead to them to migrate similarly in gel electrophoresis. For example, carminic acid is similar to Yellow 6, betanin acid bears resemblance to Yellow 5, fast green FCF is like Blue 1, and citrus red 2 resembles Red 40.

        Our dyes ran mostly as expected, with the orange dye being Yellow 6, and the other dyes turning out to be their corresponding reference dyes. However, our green dye separated into 2 different bands when we ran the gel electrophoresis. This green was actually a mixture of a blue and a red dye (Blue 1 and Red 40), since green dyes are likely harder to produce.

Final gel results (4 test dyes on left, 4 reference dyes on right)

        The colored dye solutions we used also migrated different distances, and this effect was contributed to by multiple factors. First of all, the larger molecules are less flexible and will be hindered more by the gel’s channels. Also, the molecule concentrations would make a difference: a dye with a higher concentration might advance slower than another dye with a lower concentration.

Gel electrophoresis setup

        The movement of the dyes through the gel is facilitated by their negative charge and the voltage of the electricity. Their charge makes them attracted toward the anode, and smaller molecules can advance further, because they are less obstructed by imperfections and twists in the gel. DNA molecules, which are commonly used in gel electrophoresis, would also separate like the dyes we used. DNA of a lower dalton size would advance the furthest, while the largest molecules would advance much slower and thus traverse less distance.