[Illinois] ECE 416 DNA Microarrays I

By Brian Cunningham

University of Illinois at Urbana-Champaign

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;In this lecture, we started off with a revision of DNA with genes and gene expressions and how DNA sends messages. The problem with gene detection is how to analyze expressions with thousands of genes and determine what possible physiological processes a gene may be related to. All cells have the same genome, but each cell can express different set of proteins. The mRNA sequences present in a cell can be seen with a DNA Microarray. On a surface, you can print thousands of individual gene sequences applied in a grid of "spots" to surface of a glass slide or a biosensor. There are two main types of arrays: long and short. But in both of them if a sequence is presented a fluorescent tag is attached and then excited with a laser so we can observe them. In long strand DNA Microarrays, the portion of coding region of gene to be analyzed is individually amplified by PCR. The DNA is covalently bound to the surface and the attached DNA is denatured leaving a single-strand DNA molecule attached. There are different DNA Array spot making methods, using pin-based or ink jet. It is difficult to make perfect spots all the time, so some are replicated in different areas so the results are not ruined by a "bad" spot. The short strand DNA Microarray method uses a "light detected synthesis" method and several nucleotide sequences from a single gene are synthesized in neighboring regions. In order to make these microarrays, each gene is built one base pair at a time and how they are made is discussed in further detail. For detection, an array of immobilized single-strand DNA "probes" is used to capture fluorescently tagged DNA targets from the test sample. The probe-target binding is only strong when base pairs are exactly complementary to each other. The fluorescent tags are attached to the detected (analyte) DNA and the ratio of the colors of the sample to the control is used to figure out detection of the molecules.





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  • Brian Cunningham (2013), "[Illinois] ECE 416 DNA Microarrays I," http://nanohub.org/resources/17701.

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University of Illinois, Urbana-Champaign, IL


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