Array can be defined as to place in an orderly arrangement. It is important that the gene sequences in a microarray are attached to their support in an orderly or fixed way, because a researcher uses the location of each spot in the array to identify a particular gene sequence. The spots themselves can be DNA, cDNA, or oligonucleotides. Microarrays can be broadly defined as tools for massively paralleled ligand binding assays where features (e.g. oligonucleotides) are placed on a solid support (e.g a glass slide) at high density for recognising a complex mixture of target molecules. ascunde descrierea