The purpose of this book is to account for the structure and function of genes in terms of extensive knowledge about both prokaryotes and eukaryotes. It explains what a gene is, how it is reproduced and what controls its expression. This new edition has completely new chapters on protein trafficking and eukaryotic gene transcription. It has a new introduction to the subject, making the book more approachable to less advanced students. Chapters on bacterial transcriptions, post-transcriptional control, interrupted gene structure, RNA splicing, transposons in bacteria, transposable elements in eukaryotes, gene expression in development, and the role of oncogenes in carcinogenesis have been completely rewritten.