So if we had the right sugars, phosphates, and acids we would not get DNA.
Well, not exactly. The nucleotides - A,C,T, and G - have been shown to form abiotically. But these would not self assemble long polymers of double stranded DNA.
I am aware of the role of the polymerase and GTP but did not know if the barrier without them could be overcome.
I'm not sure exactly what you mean here. DNA can be replicated with just polymerase and a source of nucleotides. That's basically what PCR is - a machine just cycles through temperatures, and DNA unwinds, primers anneal and polymerase copies - all ex vivo. Before our school bought a PCR machine, I used to have my students put the ingredients in a tube and move the tube from water bath to water bath, all at different temperatures, and DNA was copied. I'm not saying this is how things worked 3 bya, only that it is theoretically possible for DNA rep to occur outside a cell with the right conditions. That said, I am unaware of any models of abiosynthesis that suggests this is how things happened. Most suggest RNA evolved as the initial molecule of heredity, and DNA co opted RNA and its ability to produce proteins (such as polymerase) later in evolution.
Now with RNA, can it make a chain from nothing? If you had a solution of these parts do they chain together? Or are they limited to replicating an existing chain?
Yes, RNA will self assemble into polymers, and these polymers are capable of acting as enzymes (much like proteins) and can catalyze RNA synthesis. In fact, a Nobel prize was awarded for
this discovery. Now, they are limited in how long they can be - and I don't know if chains link together. But the point is (from an evolutionary perspective) that heritable, self replicating material can form naturally -and this is all that is required for natural selection to act (selecting some RNAs with certain features that make them "better" than other RNAs).
Once a chain is formed does it fall into an energy well so it is not likely to disassemble?
Well, I don't know. But all that is required for evolution to act is that they remain stable long enough for selection to favor some variants over others. And perhaps one thing that is being selected is stability. (?)
Is there any theory how an RNA molecule could make a DNA molecule?
Well, there are 2 possibilities here; first that RNA acted as an enzyme (see the Nobel prize stuff) to catalyze the replication of DNA. The second, and more probable explanation is that RNA produced short proteins (this is, after all, what they do in cells) and some of those proteins acted as catalysts to produce DNA (much like polymerases do today). In other words, evolution may have favored an RNA that produced an enzyme that produced DNA (a more stable form of heritable material).
I know this is a stretch, but at some point you have to describe all parts needed and show how each arrived through natural processes.
Well, I am a bit reluctant to use anthropogenic examples because we're starting with a bias - that the structure was intelligently designed, for a purpose, with parts made by a designer. In the example you cite, the answer is yes - the parts have to come from a designer. But the answer from abiogenesis is "no" - the parts can and have been shown to arise from abiotic precursors without divine intervention. Experiments over the last 60 years have confirmed this. This doesn't mean that is how it all happened, only that it is possible that this is how it all happened.
I have read that some people are saying that early precursers may have been way different and since we don't have them anymore we may never know how this happen. I just see this as a cop out.
I would have to see the context in which this statement was made. For example, the original
Miller-Urey experiment showed that organic molecules could arise from inorganic precursors. But that was 60 years ago - and critics have argued that their conditions may not have mirrored those conditions believed to exist on ancient Earth. And I think these are fair criticisms - later geologic evidence may have shown that life evolved in conditions with far less oxygen. Some critics believe the origins of life occurred in deep hydrothermal vents. Others that life was seeded from comets. Each of these models have been tested, and each enjoys varying degrees of support. But the bottom line is that it is difficult, if not impossible to exactly recreate the sequence of events leading to the evolution of life - events that occurred 3.5 billion years ago in conditions not known with absolute certainty and that did not leave traces in a fossil record. But this doesn't mean hypotheses can't be developed and tested refined as new evidence comes to light.
It is my understanding that a virus requires the replicator of its host in order to duplicate.
Hm. No. Not exactly. Depends on the virus; depends on the host. Minimally a virus just needs to enter a host to replicate. And they usually use energy and molecules from the host to do this. Some viruses pre-package their own replicator molecules (like HIV and reverse transcriptase).
This means that the earliest forms had to be replicators. But replicators are not simple.
Yes, and no. RNA is a replicator, and at only a handful of nucleotides long, it's pretty simple.
So I hope to pick your brain for as long as you let me.
Longer than I'd let you pick my nose...
It only looks designed since we EXIST! Out of the billions of worlds in this Universe, there should be at least one in the perfect spot! Do IDers believe this was the spot where God decided to put Earth? Why would God choose this galaxy and this location within it? Not really addressable questions but I thought I'd throw it out there
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