Genes, genomes, and chips

Abstract This chapter provides an overview of the microarray or biochip field, describing biological framework, historical perspective, applications, and future trends. Microarray assays are summarized and compared to traditional approaches. Methodological underpinnings of biochips are emphasized. The information content of the genome is carried hereditarily as deoxyribonucleic acid (DNA). The size and composition of a given genomic sequence determines the form and function of the resultant organism. In general, genomic complexity is proportional to the complexity of the organism. Relatively simple organisms such as bacteria have genomes in the 1– 5 million base (megabase) range while mammalian genomes including human are approximately 3000 megabases; genomes from organisms of intermediate complexity such as worms and insects are typically 100– 200 megabases.