enzymes, or ribozymes, are found in today's DNA-based life and could be examples of living fossils. Ribozymes play vital roles, such as that of the ribosome. The large subunit of the ribosome includes an rRNA responsible for the peptide bond-forming peptidyl transferase activity of protein synthesis. Many other ribozyme activities exist; for example, the hammerhead ribozyme performs self-cleavage and an RNA polymerase ribozyme can synthesize a short RNA strand from a primed RNA template. Among the enzymatic properties important for the beginning of life are: Self-replication The ability to self-replicate, or synthesize other RNA molecules; relatively short RNA molecules that can synthesize others have been artificially produced in the lab. The shortest was 165 bases long, though it has been estimated that only part of the molecule was crucial for this function. One version, 189 bases long, had an error rate of just 1.1% per nucleotide when synthesizing an 11 nucleotide long RNA strand from primed template strands. This 189 base pair ribozyme could polymerize a template of at most 14 nucleotides in length, which is too short for self replication, but is a potential lead for further investigation. The longest primer extension performed by a ribozyme polymerase was 20 bases. In 2016, researchers reported the use of in vitro evolution to improve dramatically the activity and generality of an RNA polymerase ribozyme by selecting variants that can synthesize functional RNA molecules from an RNA template. Each RNA polymerase ribozyme was engineered to remain linked to its new, synthesized RNA strand; this allowed the team to isolate successful polymerases. The isolated RNA polymerases were again used for another round of evolution. After several rounds of evolution, they obtained one RNA polymerase ribozyme called 24-3 that was able to copy almost any other RNA, from small catalysts to long RNA-based enzymes. Particular RNAs were amplified up to 10,000 times, a first RNA version of the polymerase chain reaction (PCR). Catalysis The ability to catalyze simple chemical reactions—which would enhance creation of molecules that are building blocks of RNA molecules (i.e., a strand of RNA that would make creating more strands of RNA easier). Relatively short RNA molecules with such abilities have been artificially formed in the lab. A recent study showed that almost any nucleic acid can evolve into a catalytic sequence under appropriate selection. For instance, an arbitrarily chosen 50-nucleotide DNA fragment encoding for the Bos taurus (cattle) albumin mRNA