Running an Agilent RNA gel for Affymetrix work with a soundtrack by System of a Down (Science).
The nanochip separates RNA by size.
HOW: It is a bit like dropping a piece of flat paper and a piece of screwed up paper - air resistance will make the bigger thing fall more slowly.
In this case there is an electrical pull instead of gravity, and there is a semi-solid gel instead of air for resistance, but the idea is the same.
Why separate it by size ?
Because this alows you to look at the types of RNA in a sample, you can see how good it is (structurally, not morally). If it is undamaged, you can use it to decode all of the information (RNA) in a sample.
