Microarray

Microarry chips are devices that enable the scientist to simultaneously measure the transcription level of every gene within a cell. Microarrays are commercially available from a number of companies, such as Affymetrix, Invitrogen and Sigma-Genosys, to name a few. The chip is usually constructed by amplifying all the genes within the selected genome, yeast, for example, using polymerase chain reaction (PCR) methodology. The PCR products would then be "spotted" onto the chips by a robot, as single-stranded DNA that is linked by covalent bonds to the glass slide. The spots would be positioned in an array on a grid pattern, where each spot contains many identical copies of an individual gene. A discussion of the chemistry involved in creating a microarry can be found on the technology page of the Affymetrix website. The position of the genes are recorded by spot location, so that the appropriate gene can be identified any time a probe hybridizes with, or binds to, its complementary DNA strand on the chip.