<prompt> Microarray isStudy of multiple genesStudy of diseaseStudy of organismsStudy of blood group  <response>: A DNA microarray also commonly known as DNA chip or biochip is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. Each DNA spot contains picomoles 10-12 moles of a specific DNA sequence, known as probes or repoers or oligos. These can be a sho section of a gene or other DNA element that are used to hybridize a cDNA or cRNA also called anti-sense RNA sample called target under high-stringency conditions. Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target. The original nucleic acid arrays were macro arrays approximately 9 cm x 12 cm and the first computerized image based analysis was published in 1981. Ref Robbins 9e p263 