quote:
I was wondering what the current theories are as to early DNA replication systems. It seems that life could never have been passed on if there was never a precursor to the Polymerases we see today. In fact, would there not have had to be a replication system at the time of the first cell being formed? I've done some research, however, the only thing I can find on polymerases are descriptions of function, and nothing touching on the evolutionary precursors to it.
The answer is that DNA may not have been the first genetic material. RNA can carry both genetic information and carry out chemical reactions. The RNA World Hypothesis states that the first replicators may have been short stretches of RNA that carried out chemical reactions that resulted in self replication. This may have required RNA to build polypeptides, copy itself, or make new and different RNA molecules.
For an overview I would check out
this site. And an excerpt from that site:
Today, research in the RNA world is a medium-sized industry. Scientists in this field are able to demonstrate that random sequences of RNA sometimes exhibit useful properties. For example, in 1995, a group of researchers reported "Structurally Complex and Highly Active RNA Ligases Derived from Random RNA Sequences" (4). (Ligases are enzymes that splice together other molecules such as DNA or RNA.) The results are interestingthey suggest that randomness can produce functionality. The authors interpret the results to mean that "the number of distinct complex functional RNA structures is very large indeed."