A
DNA microarray (also commonly known as
DNA chip or
biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the
expression levels of large numbers of genes simultaneously or to
genotype multiple regions of a genome. Each DNA spot contains
picomoles (10
-12 moles) of a specific DNA sequence, known as
probes (or
reporters or
oligos). These can be a short section of a
gene or other DNA element that are used to hybridize a
cDNA or cRNA (also called anti-sense RNA) sample (called
target) under high-stringency conditions. Probe-target hybridization is usually detected and quantified by detection of
fluorophore-, silver-, or
chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target.