Figure 1

A popular model for the development of the genetic system. The RNA world hypothesis proposes that the first genetic system involved informational RNA molecules that encoded the synthesis of modestly functional RNA molecules [1]. Protein translation developed during this period leading to the RNA-protein world. Finally, protein enzymes produced deoxyribonucleotides through ribonucleotide reduction. The availability of deoxyribonucleotides led to the establishment of the DNA genome and the modern genetic system [5].