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Horizon Education and Media
Gel Electrophoresis (DNA fingerprinting process) done with home materials by our Horizon class
To "get" the concept of DNA fingerprinting it is easiest to do the lab and figure out the concepts while doing so.
DNA Fingerprinting is a method of analyzing each person's DNA by cutting it into short sections of different sizes and pulling the DNA through a gel. Each person has a different pattern of bands according to how large each cut DNA section is. We can analyze the band pattern to see relatedness between people or to match someone to a crime.
DNA Fingerprinting is done using a gel and electricity to separate the bands, called Gel Electrophoresis. The smaller the molecule is, the further it will go.
In this activity we will use the Exploratorium Gel Electrophoresis activity, sightly adapted to make it work better as a DIY activity using at-home materials.
Tap the Science Snack Gel Electrophoresis (Exploratorium) instructions to set up and run the lab.
When this lab was tested for this course, the concentration instructions needed adjustment and some of the materials were only found in a lab-based situation. A household-friendly materials list that can be easily found in a local grocery store, and adjusted concentrations instructions is available in the Parent Guide.
The video provides very detailed instructions.
The two wire electrodes pull the dyes through the gel, starting in the small rectangular wells near the top of the picture. The wire electrode at the top is negative and bubbling as water molecules are separated and hydrogen gas is released. The wire electrode at the bottom of the picture (not shown) is positive, which pulls the negative-charged dye molecules downwards. At the positive electrode, oxygen is released.
DNA and food dyes are negatively charged, so move to the positive electrode (red wires, + sign).
The smaller molecules (yellow) move faster, separating out from the larger molecules (blue).
From the desk of Hannah Robinson
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