DNA microarray: Difference between revisions

Revision as of 02:24, 1 July 2003

Revision as of 02:50, 1 July 2003

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Because '''"GeneChip"''' is a trademarked name owned by [[Affymetrix]], scientists tend to speak and write about "gene chips" only in reference to the chips that Affymetrix makes. Brought to market in [[1996]], these were the first to come into use, and they are referred to generically as '''oligonucleotide arrays,''' because the probe sequences are short pieces of DNA about 10 to 50 [[nucleotide]]s long. A still broader term is '''microarray''', which refers not only to GeneChips but 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 oligonucleotides probes as well as on the means the company uses to affix them to the chip, microarrays that are not made by Affymetrix are manufactured by a different technique that is non-proprietary.

Typically arrays are used to detect the presence of different [[mRNA]]s in an extract from a sample of cells from a single tissue. If mRNA binds to the spot on an array to which a specific probe sequence has been affixed, that implies that the cells are actively [[transcription|transcribing]] a gene with a sequence complementary to that probe (see "anti-sense" under [[DNA]]).

Using microarrays, cancerous cells can be analyzed with gene chips to discover which genes are present in the cancerous cells that are not present in healthy cells. Cells can be treated with drugs, and the gene chip can analyze those genes to determine which genes are turned on or off by the drug.

Researchers usually employ microarrays in a comparison between two samples. For example, an RNA sample from [[brain tumor]] cells, might be compared to a sample from healthy [[neuron]]s or [[glia]]. Probes that bind RNA in the tumor sample but not in the healthy one indicate genes that are uniquely associated with the disease. Such identifications can lead to candidate targets for drugs.

Since there are hundreds of thousands of probes on a gene chip, using a gene chip can be the equivalent of thousands of conventional genetic tests. Gene chips have therefore dramatically accelerated the pace of genetic research.