Science Buddies: "Ask an Expert"

Hi there!

For my grade 10 science project my partner and I have decided to create a small electrophoresis chamber to compare the pigments in similarly coloured flowers. "What is the relationship between the colour similarities of different species of plants and their biological pigment?" is our statement of purpose.

We've already done a lot of background research on how electrophoresis works but we are unsure on how to proceed with the project, particularly how we are going to use electrophoresis to compare plants' pigments.

My first question is how exactly can we extract the pigments? I've read online that the plant should be crushed and mixed with alcohol and strained so only a coloured liquid remains, but how much of either material should I add? And would I need to keep the measurements exact for all the pigment samples?

My second question is if we run the pigment samples the same way DNA samples are run through the chamber?

Lastly, how do we compare the final result? Do we just compare the different bands created by the different pigment samples, and pick out the similarities and differences?

Many thanks,
rainbodino

Hi,

That's an interesting and colorful subject! There's one problem I see right away, however, and that is that electrophoresis separates molecules according to charge and if they aren't charged they won't run on the gel. Electrophoresis works fine for DNA which has a negative charge because of all the phosphate groups; and proteins often have a net negative or positive charge, or can be modified with sodium dodecyl sulfate to be negatively charged. Plant pigments such as carotenes, anthocyanins or chlorophylls are complex organic molecules that may not have a net electrical charge. You would have to do some research on that.

Pigments are often separated by the process of paper chromatography and you might want to check out that method: https://www.sciencebuddies.org/science- ... structions

There are other ways to separate pigments but many of them use toxic or flammable solvents that you would not have access to. The electrophoresis separation idea is interesting and it could work if the pigments are charged. Do some more research online and let us know what you find out and we will try to help you develop a good project.

Good luck!

Sybee