DNA Sequencing with Arrays

Constructing arrays with longer oligomers enables the analysis of longer stands of sample DNA. However, fabrication of the array becomes more complex as the required number of spots increases exponentially. For example, octanucleotides 

The immobilised molecule is either an oligonucleotide or a strand of cDNA (section 6.2.5). Oligonucleotides consist typically of between 25 and 70 nucleotides. These can either be prefabricated and spotted onto the array surface or directly synthesised on the glass surface, as outlined for the Affymetrix GeneChipT. cDNA is obtained from isolated RNA by reverse transcription (section 6.2.5). After PCR amplification, cDNA strands of between 500 and 5000 bases are usually immobilised on the array substrate. 

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