Posted: Mar 31, 2010 4:52 pm
by Rumraket
byofrcs wrote:
rainbow wrote:
Rumraket wrote:
rainbow wrote:
Better replicators, like RNA would have totally replaced any simpler precursors, and since we are talking about events that happened over 3.8 billion years ago, much, if not all information could be lost.

Invisible Pink Unicorns might also exist, but we have no way of knowing either, do we?

It's a bad equivocation. By inference from evolutionary principles we would have reason to believe in increasingly reliable and complex replicators. Obviously we can't just assert it, but there is a basis for researching the possiblity.

In contrast, we don't have any empirical evidence on which to assert the existence of pink Unicorns. On that basis, I think it would also be a waste of time and research money to start looking for them.

Absolutely no doubt, I'd like to see research on making a simpler replicator. A little collection of molecules that can make copies of itself, and sometimes making mistakes in that copying - leading to an improved, evolved version.

It would not even need to be based on the exact same chemistry of known life.
The applications in medicine and industry could be enormous.
Money well spent, I would say.

That's the idea here. There probably are novel applications but for replication today we can just hijack bacteria.

That's awesome, but i'm confused. Myers states :
PZ Myers wrote:Another cool thing about this experiment is that the enzymes proved to be efficient and robust. Below, you can see that they acheived exponential growth, only leveling out when the substrates were exhausted.

And goes on further:
PZ Myers wrote:These enzymes worked well. If they were producing deleterious byproducts that were interfering with the reaction, you'd expect to see a gradual decline in the rate that was independent of the reduction in concentration of the substrates; no such effect was observed in the experiment below, where substrates were regularly replenished. These paired chemical replicators were just cruising, reliably making lots of copies of themselves, and they could keep going for ages…like, 4 billion years.

And this is where I get confused. In the latest Szostak paper on attempting to find reliable replicators it is stated:
Efficient and Rapid Template-Directed Nucleic Acid Copying Using 2′-Amino-2′,3′-dideoxyribonucleoside-5′-hosphorimidazolide Monomers
We have also demonstrated repeated cycles of growth and division for fatty acid vesicles without loss of encapsulated aterial.4 However, no general nucleic acid copying mechanism has been demonstrated with the capacity to function as a self-replicating protocellular genome, even though many ribozyme-mediated and nonenzymatic genetic polymer replication schemes have been investigated.5-10 Ribozymes such as the naturally occurring sunY and Tetrahymena self-splicing introns or the in Vitro evolved class I and R3C ligases and polymerases are able to assemble short oligonucleotides or ononucleotides in a template-directed manner. All, however, lack the high reaction efficiency and sequence-general copying ability required for the replication of a protocell genome.11-16

The Szostak-lab paper is specifically citing the Joyce et al paper in citations 11-16(paper # 15).

So, uhh... I guess the confusion may lie in my lack of understanding of how "reaction efficiency" and "sequence-general copying ability" in the [E catalyzes A+B => E']-selfreplicator failed to live up to "requirements" for protocell genomes.

Sum1 enlighten me pleaze :)