OK I have read that a cell generates 4 kinds of digital (to be precise discrete) data namely DNA, RNA, Protein (sequences that can be encoded as string sequences of nucleotides/ amino acids) and micro array image. I am not a biologist, but my interest is in the statistics and information theory of these data. I would like to know what information do DNA micro array image convey? For example after processing it with the aid of a suitable software, what sort of information we do obtain?

Sample micro array image:

enter image description here

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    $\begingroup$ In the general case the color simply indicates how much of a specific RNA or DNA is in your sample. What you get out of this depends heavily on the exact experiment you're performing. $\endgroup$ May 12, 2014 at 12:31
  • $\begingroup$ Where can I get more information? What is the relation of micro array image with gene expression? $\endgroup$
    – dexterdev
    May 12, 2014 at 13:30
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    $\begingroup$ en.m.wikipedia.org/wiki/DNA_microarray In the context of an expression level experiment, each spot represents a unique oligonucleotide probe. The relative colour intensity of each spot tells you the relative abundance of RNA in the cell that hybridizes to that probe. $\endgroup$
    – canadianer
    May 12, 2014 at 14:17
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    $\begingroup$ The color is because of a fluorescent tag (Cy3/Cy5) attached to the DNA that you hybridize to the array. $\endgroup$
    May 12, 2014 at 14:50

1 Answer 1


Each spot overlaps with an oligonucleotide probe, that is designed to identify a specific nucleic acid sequence. Gene expression arrays have probes which are complementary to sequences derived from the exons; therefore they will hybridize with these sequences.

Before hybridization the cDNA (in this case) is labeled with a fluorescent molecule such as Cy3 or Cy5 (two dyes can be used to differentiate treated and control). Note that each spot will have many probe molecules. Fluorescent intensity is proportional to number of hybridized DNA strands, which in turn is proportional to its expression in the sample.

Extensive amount of texts are available on microarray data analysis which you can find quite easily.


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