Genetic Code Evolution in the RNA World and Beyond

Abstract

Although the translation apparatus presumably arose in an RNA world, subsequent modifications obscure its origins. The genetic code, fixed in the Last Universal Ancestor may contain clues about the types of chemical interaction that led to early correspondences between RNA arid protein. The extent to which contemporary translation reflects these primordial influences depends on the processes that have shaped the genetic code since its inception: stereochemical interaction between amino acids and RNA, bistorical constraints ensuring continuity between successive codes, and optimization to minimize the effects of errors caused by translation arid mutation. This chapter explains how these processes, typically presented as mutually antagonistic, may actually be viewed as complementary oil different timescales, and I suggest how the "first" codons could have been established in the context of air RNA world.