Genetics : from genes to genomes The science of genetics is less than 150 years old but its accomplishments within that short time have been astonishing. Gregor Mendel first described genes as abstract units of inheritance in 1865; his work was ignored and then rediscovered in 1900. Thomas Hunt Morgan and his students provided experimental verification of the idea that genes reside within chromosomes during the years 1910 1920. By 1944 Oswald Avery and his coworkers had established that genes are made of DNA. James Watson and Francis Crick published their pathbreaking structure of DNA in 1953. Remarkably less than 50 years later (in 2001) an international consortium of investigators deciphered the sequence of the 3 billion nucleotides in the human genome. Twentieth century genetics made it possible to identify individual genes and to understand a great deal about their functions. Today scientists are able to access the enormous amounts of genetic data generated by the sequencing of many organisms genomes. Analysis of these data will result in a deeper understanding of the complex molecular interactions within and among vast networks of genes proteins and other molecules that help bring organisms to life. Finding new methods and tools for analyzing these data will be a significant part of genetics in the twenty first century. Our seventh edition of Genetics: From Genes to Genomes emphasizes both the core concepts of genetics and the cutting edge discoveries modern tools and analytic methods that will keep the science of genetics moving forward. The authors of the seventh edition have worked together in revising every chapter in an effort not only to provide the most up to date information but also to provide continuity and the clearest possible explanations of difficult concepts in one voice