This book is an introduction to the world of gene cloning assuming almost no background knowledge. In the second edition the author has responded to quickening interest in biotechnology by contributing separate chapters on gene cloning applications to medicine and agriculture. New topics in medicine are diagnosis (via DNA probes) and research into genetic diseases, the use of gene cloning in research into cancer and AIDS, and genetic fingerprinting. The agriculture chapter will survey current research into crop improvements. The author has updated the book (three years is a long time in gene research), and added new material whenever appropriate. Among the new topics are some new vectors; the polymerase chain reaction; genomic and RNA sequencing; and analysis of DNA-protein interactions.