The genetic code was deciphered experimentally around 1966 and for a number of years scientists considered it to be "universal" for all forms of life. In 1981 researchers shocked the scientific community with the discovery that the code differed in mitochondria and certain other organisms, evidence that the genetic code was still evolving. This book discusses the distribution and origin of the non-universal codes and examines the possible mechanisms of code changes, making it essential reading for all those interested in evolutionary genetics.

This book is a printed edition of the Special Issue "The Origin and Evolution of the Genetic Code: 100th Anniversary Year of the Birth of Francis Crick" that was published in Life

Early Thoughts on RNA and the Origin of Life The full impact of the essential role of the nucleic acids in biological systems was forcefully demonstrated by the research community in the 1950s. Although Avery and his collaborators had identified DNA as the genetic material responsible for the transformation of bacteria in 1944, it was not until the early 1950s that the Hershey-Chase experiments provided a more direct demonstration of this role. Finally, the structural DNA double helix proposed by Watson and Crick in 1953 clearly created a structural frame work for the role of DNA as both information carrier and as a molecule that could undergo the necessary replication needed for daughter cells. Research continued by Kornberg and his colleagues in the mid-1950s emphasized the biochemistry and enzymology of DNA replication. At the same time, there was a growing interest in the role of RNA. The 1956 dis covery by David Davies and myself showed that polyadenylic acid and polyuridylic acid could form a double-helical RNA molecule but that it differed somewhat from DN A A large number of experiments were subsequendy carried out with synthetic polyribonucleotides which illustrated that RNA could form even more complicated helical structures in which the specificity of hydrogen bonding was the key element in determining the molecular conformation. Finally, in I960,1 could show that it was possible to make a hybrid helix.

This is a detailed history of one of the most important and dramatic episodes in modern science, recounted from the novel vantage point of the dawn of the information age and its impact on representations of nature, heredity, and society. Drawing on archives, published sources, and interviews, the author situates work on the genetic code (1953-70) within the history of life science, the rise of communication technosciences (cybernetics, information theory, and computers), the intersection of molecular biology with cryptanalysis and linguistics, and the social history of postwar Europe and the United States. Kay draws out the historical specificity in the process by which the central biological problem of DNA-based protein synthesis came to be metaphorically represented as an information code and a writing technology—and consequently as a “book of life.” This molecular writing and reading is part of the cultural production of the Nuclear Age, its power amplified by the centuries-old theistic resonance of the “book of life” metaphor. Yet, as the author points out, these are just metaphors: analogies, not ontologies. Necessary and productive as they have been, they have their epistemological limitations. Deploying analyses of language, cryptology, and information theory, the author persuasively argues that, technically speaking, the genetic code is not a code, DNA is not a language, and the genome is not an information system (objections voiced by experts as early as the 1950s). Thus her historical reconstruction and analyses also serve as a critique of the new genomic biopower. Genomic textuality has become a fact of life, a metaphor literalized, she claims, as human genome projects promise new levels of control over life through the meta-level of information: control of the word (the DNA sequences) and its editing and rewriting. But the author shows how the humbling limits of these scriptural metaphors also pose a challenge to the textual and material mastery of the genomic “book of life.”

The genetic code is one of the greatest discoveries of the 20th century as it is central to life itself. It is the algorithm that connects 64 RNA triplets to 20 amino acids, thus functioning as the Rosetta Stone of molecular biology. Following the discovery of the structure of DNA by James Watson and Francis Crick in 1953, George Gamow organized the 20-member "RNA Tie Club" to discuss the transmission of information by DNA. Crick, Sydney Brenner, Leslie Barnett, and Richard Watts-Tobin first demonstrated the three bases of DNA code for one amino acid. The decoding of the genetic code was begun by Marshall Nirenberg and Heinrich Matthaei and was completed by Har Gobind Khorana. Then, finally, Brenner, Barnett, Eugene Katz, and Crick placed the last piece of the jigsaw puzzle of life by proving that UGA was a third stop codon. In the mid-1960s, Carl Woese proposed the "stereochemical hypothesis", which speculated that the genetic code derives from a type of codon-amino acid-pairing interaction. The origin and evolution of the genetic code remains a mystery despite numerous theories and attempts to understand these. In this Special Issue, experts in the field present their thoughts and views on this topic. Because 2016 commemorated the 100th anniversary of the birth of Francis Crick, the Guest Editor of this Special Issue also dedicates all articles included herein to the memory of Francis Crick.

The ability to introduce non-canonical amino acids in vivo has greatly expanded the repertoire of accessible proteins for basic research and biotechnological application. Here, the different methods and strategies to incorporate new or modified amino acids are explained in detail, including a lot of practical advice for first-time users of this powerful technique. Novel applications in protein biochemistry, genomics, biotechnology and biomedicine made possible by the expansion of the genetic code are discussed and numerous examples are given. Essential reading for all molecular life scientists who want to stay ahead in their research.

The second part of the book focuses on codon usage bias.