Re: Can jello be used in place of the agarose gel used in electrophoresis?

Hi Ralph,

Thanks for submitting your question to the MadSci network. It sounds like you perhaps want to save some money on a project by substituting the Jell-O brand gelatin powder (or some comparable food-grade gelatin product) you can buy at your local grocery store for the purified agarose powder used by molecular biologists and biochemists.

At a first inspection, this might seem like a good idea. Both powdered gelatin and powdered agarose will dissolve in water and form a semi-solid gel. Depending on the concentration that is used, you can make a more or less firm/solid gel, as dictated by your needs.

In fact, before agarose was used as a growth medium for bacterial cultures (in Petrie plates or on slants), gelatin was used for the same purposes. I've discussed the history of agarose and the appeal of its use for microbiology over gelatin in this answer in our archives (1058224624.Bc).

However, in reading that answer, you can perhaps see that the reason why agarose is preferred over gelatin as a bacterial growth medium is the same reason why agarose should be used for electrophoresis instead of gelatin. If you've done any gel electrophoresis, you know that the gel apparatus can get very hot. This is because of the high voltages that are used in electrophoresis. The melting temperature of an agarose gel is 100 degrees centigrade, but the melting temperature of a gelatin block can be somewhere around body temperature (depending on the purity and concentration of the gelatin used). So, electrophoresis gels made of gelatin will most likely melt when used. Even if they don't completely melt, such gels will likely lose integrity, so that it will be difficult to interpret the results of your experiment correctly.

So, you can't use gelatin for your experiment. Do you have to use the really expensive purified agarose sold by biological supply companies? The answer depends on how precise you need your experiment to be. As you will notice in the answer I linked to above, Agar-Agar was used as a food additive long before it was used for bioscience. You should be able to find food-grade agar in a specialty grocery store. Try your experiment with a gel made from that, and then you can decide if you want to purchase the expensive high-grade stuff.

Good luck!