text: The RNA world hypothesis assumes that very early in evolution, prior to the emergence of DNA as a genetic material and prior to the emergence of protein enzymes, RNA was the key player in the emergence of life.  A central idea in this hypothesis is an RNA replicase (ribozyme) that is capable of copying its own genome. A holopolymerase ribozyme has been engineered that uses a sigma factor-like specificity primer to recognize an RNA promoter sequence. This ribozyme can then, in a second step rearrange to a processive form that can polymerize from certain RNA promoters and not others.