By this directed evolution we were able to
produce ribozymes that can catalyze the copying of relatively short strands of other RNAs, although they fall far short of being able to copy polymers with their own sequences into progeny RNAs.
In 1993 David Bartel, then a graduate student with Szostak,
produced a ribozyme that could join another piece of RNA to itself.
Not exact matches
RNA organisms could evolve new
ribozymes as well and also
produce them in bulk as they multiplied.