This completely revised and updated edition takes advantage of the many new advances in biology since the publication of the first edition, including the sequencing of the human genome, the genomes of a wide variety of other organisms, and the increased use of transgenic animals for understanding the molecular basis of human and animal disease. It also provides a much-needed update on the new techniques currently employed and to help redefine and illustrate the important roles still to be palyed by yeast artificial chromosome (YAC) technologies in the postgenomic age.