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How DNA chips work

The test sample of DNA is first unzipped (i.e. the DNA double helix is unwound and pulled apart) by heating, then labelled with a dye, and washed over the chip. A DNA chip relies on the natural ability of a DNA strand to stick to a 'complementary copy' of itself: the letter A always pairs up with a T, and a C with a G. Any gene in the sample that matches a fragment on the chip will stick to it, and show up as a brightly coloured dot..

A DNA chip array.
A DNA chip array.
US Department of Energy Human Genome Program (www.ornl.gov/hgmis)

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