An ordered array of DNA probes providing a powerful reagent for analyzing the genome. Recently, the completion of the analysis of the human genome has elucidated its entire sequence. DNA is the blueprint of life and encodes all of the genes that are expressed from the genome in the form of messenger ribonucleic acid (mRNA). The mRNA is translated by cellular machinery into proteins. Determining the sequence of the entire genome allows a comprehensive analysis of all genes, and hence proteins, that make up cells, tissues, and the entire organism. There is now access to the complete genome sequence of hundreds of bacteria and 25 eukaryotes, including yeast (Saccharomyces cerevisiae, 6200 genes encoded in about 12 million base pairs), worm (Caenorhabditis elegans, 18,000 genes encoded in about 80 million base pairs), fruit fly (about 200 million base pairs), and mouse (about 3 billion base pairs). As of 2003, highly accurate sequencing of the human genome (about 3 billion base pairs encoding an estimated 25,000 protein-coding genes) has been available.