Revised, updated, and expanded since first appearing in 1993, this work offers the molecular biologist thorough treatment of both the hypothetical NRA World and the complexities of RNA structure and function found today. Containing 24 chapters, the volume addresses topics relating to the origins of RNA, including geophysical and geochemical constraints on molecular evolution, the genomic tag hypothesis, re-creating an RNA replicase, and introns. Building functional RNA is also covered, with contributions on the interactions that shape NRA structure, small ribozymes, the role of metal ions in RNA biochemistry, and ribonuclease P. Additionally, transition to the RNP world is covered, with contributions on RNA interaction with small ligands and peptides, Group I and II ribozymes as RNPs, splicing of precursors to mRNAs by the spliceosome, RNA editing, and telomerase. Includes color and b&w illustrations and five appendices providing relevant figures and diagrams. Annotation c. by Book News, Inc., Portland, Or.