DNA microarray: Difference between revisions

Revision as of 10:20, 4 July 2003

Revision as of 10:22, 4 July 2003

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Because the name '''"GeneChip"''' is trademarked by [[Affymetrix]], microarray users tend to speak and write about "gene chips" only in reference to Affymetrix chips. Made available in [[1996]], gene chips were the first arrays to come into use. Generically they are known as '''oligonucleotide arrays,''' because the probes they use are short segments of DNA about 10 to 50 [[nucleotide]]s long.

"Microarray" refers not only to GeneChips but also to chips that use much longer probe sequences, such as the entire [[gene]]s that may be contained on [[cDNA]]s. Because, Affymetrix owns a [[patent]] both on the use of oligonucleotide probes as well as on a means to affix them to chips, microarrays not made by Affymetrix are manufactured by a different technique that is non-proprietary.

Typically arrays are used to detect the presence of [[mRNA]]s that encode different proteins. The RNA is extracted from many cells of a single type, then converted to cDNA and "amplified" in [[concentration]] by [[reverse transcriptase]]-[[PCR]]. [[Fluorescent tag]]s are chemically attached to the strands of DNA. A cDNA [[molecule]] that contains a sequence complementary to one of the single-stranded probes will stick via base pairing (more at [[DNA]]) to the spot on the array where the probe is affixed. The spot will [[fluorescence|fluoresce]] (glow) when examined.

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The lack of standardization in non-commercial arrays presents an [[interoperability problem]] in [[bioinformatics]], which hinders the exchange of array data. Many researchers use Affymetrix technology to a large extent because it is popular and standardized. At the same time, various grass-roots [[open source|open-source]] projects are attempting to fascilitate the exchange and analysis of data produced with non-proprietary chips.

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