Modern genetics began in 1900 with the rediscovery of Mendel's paper, and now the sequencing of the human genome bas brought the first century of progress in this field to a triumphant conclusion. Genetics bas entered a new era with the advent of genomic and proteomic approaches and the knowledge in no other biological discipline is advancing as rapidly as that in molecular genetics and cell biology. Proliferation of new terms inevitably accompanies such exponential growth. The sixth edition of A Dictionary of Genetics addresses the need of students and professionals to have access to an up-to-date reference source that not only defines the most recently coined terms, but in many cases also presents important ancillary encyclopedic information. A Dictionary of Genetics has a broader coverage than its name implies, since it includes definitions of strictly genetic words along with a variety of non-genetic terms often encountered in the literature of genetics. There are about 7,000 definitions, and tables or drawings that illustrate 395 of these. In addition to the main body of the dictionary, this work features new Appendices covering the genomic sizes and gene numbers of about 30 organisms ranging from the smallest known virus to humans, an up-to-date listing of internet addresses for easy access to genetic databanks, and developments, inventions and advances in genetics, cytology, and evolutionary science from the past 400 years. These 900 entries, covering a period from 1590 to 2001, are also cross-referenced in the definitions that occur in the body of the dictionary. No other genetics dictionary supplies definitions cross-referenced to chronology entries or has species entries cross-referenced to an appendix showing the position of each organism in a taxonomic hierarchy. These features make A Dictionary of Genetics the most important lexicon in this field.