This book is a concise yet fully informative coverage of the structure and function of genes. It describes DNA and how it replicates, how DNA is transcribed and translated into proteins, the organisation of genes in prokaryotes and eukaryotes, the control of gene expression and the role of retroviruses and oncogenes in cancer. There are additional discussions of gene families, genes and the immune systems and mitochondrial and chloroplast genomes. This is a third edition of a successful undergraduate text. It has been extensively updated, particularly in regard to recent advances in our understanding of replication and transcription.