UTF-8HeidiPrinciples of Electrophoresis
Electrophoresis is a process used in analytical chemistry and biology in order to separate various components of a mixture. It can be very useful when you have a compound but are unsure what individual chemicals were put together to make the compound. For example, we could analyze gasoline using electrophoresis to determine how much octane, hexane, and other compounds are present in the gasoline we normally use. It is very commonly used in the perfume and cosmetics industries to analyze a competitor's product in order to reproduce it.
Fundamentally, electrophoresis is based on the fact that some molecules move more rapidly than others. Some molecules will move faster and others slower through a given medium, so that they spread out in even layers across the plate.
A chromatographic plate after this analysis might look something like this. The column on the left is what is called a "ladder." A ladder is a standardized mixture that has been repeatedly tested and always shows the same pattern on an electrophoresis plate. In this way you can compare the location of the sample, which is the single bar in the right column, in order to determine what it is by comparison with the compounds on the ladder.
As we've discussed, this can be extremely useful because a scientist can put any unknown substance through electrophoresis, divide it into its component parts, and determine the probable identity of each part. The important question for us today is how electrophoresis works.
The scientist first puts his samples into wells on a gel plate. Each well holds one sample and is at the bottom end of a column. The research then runs an electrical current through the wells and up the column or the gel plate. This first simulation is a simplified version of a gel plate. Each colored molecule respresents a different sample type that has been placed into a well. When we run electricity through the plate, nothing happens because these samples are not charged.
Press the Play button to watch what happens when the electricity is switched on.
Now, in order to get something more exciting to happen, the scientist has to add a medium to the plate. A medium is a solvent that will respond to the electricity and carry the particles along with it.
Notice that the new green particles all have a negative charge. They will respond to the electrical current. As they move, they will pull the other molecules along with them, dividing them into distinct layers. Just as a scientist would, use the snapshot tool to take a photograph of the reaction when each element is in a different zone of the electrophoresis plate.
This final simulation is the most like a true electrophoresis.
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In what other situations might electrophoresis be useful?
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What do you observe about the four colored particles?
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Take a snapshot of the simulation when each sample is in a different
segment of the gel plate.
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Are the results from this test the same as the previous ones? What
problems do you notice? What do you think a research might do to avoid
these problems and get duplicatable results?
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