Briefly, the GeneChip is used as follows:
- Doublestranded cDNA is synthesized from total mRNA purified from the tissue under investigation.
- cRNA, tagged with biotin, are transcribed from the double-stranded cDNA.
- The biotin-marked cRNA molecules are hybridized with the oligonucleotide probes (with known sequences) on the GeneChip.
- After washing away non-hybridized cRNA, streptavidin-phycoerythrin is added as fluorescent markers of the hybridized cRNA molecules (streptavidin binds to biotin); see Figure 3.