DNA chip

DNA chip is a popular name for oligonucleotide? probe microarray?, a technique used in molecular biology, especially genetics, to quickly scan a large DNA strand, or even a whole genome, for mutations.

Procedure

A DNA strand of known sequence (for example, a gene) is cut by restriction enzymes into short fragments (called oligonucleotides). These fragments are then tagged with a fluorescent chemical (for example, a red one), denaturated into single strands, and fixated on a chip at regular intervals.

To check another gele of the same kind for mutations, it is cut into fragments the same way as the "clean copy" has been. The fragments are tagged with a different fluorescent chemical (for example, a green one), denaturated into single strands, and given onto the prepared chip.

The unmutated fragments of the tested gene will anneal to (or hybridize? with) the fragments on the chip, showing the spot in both red and green. Fragments that carry a mutation will not anneal to a fragment on the chip, leaving the spot red.

Applications