28 Feb '11 15:22>
I was curious to know just how far scientists have got with abiogenesis research thinking it was such a difficulty subject that it would be very difficulty for them to get far on it but I was surprised to find just how far they have managed to go albeit with still many unanswered questions and gaps in our knowledge. I found this link:
http://www.talkorigins.org/faqs/abioprob/originoflife.html#RNAworld
it starts of with what I already knew:
“...Even the simplest currently living cells contain hundreds of proteins most of which are essential to their functioning. Yet such complexity cannot have stood at the origin of life. Based on research in the field it is proposed here how, once a self-replicating genetic molecule existed, life might have started and gradual evolution of complexity was made possible ...”
in other words, the first life required none of the complexity of modern life.
“...Later research had cast doubt on the existence of a reducing atmosphere, and suggested a neutral atmosphere instead – see also (Chyba 2005), the accompanying article to Tian et al. (see below).
However, new calculations indicate that hydrogen escaped from the early atmosphere at a much slower rate than previously thought, yielding an atmosphere where hydrogen was a major component (about 30 😵 and which was therefore highly reducing (Tian et al. 2005 , see also press release). ...”
the reason why the above is relevant is because a reducing atmosphere favours the right kind on chemistry for abiogenesis.
“...For a long time the synthesis of RNA monomers under prebiotic conditions appeared to be a fundamental problem since the condensation of sugar (ribose) and nucleobase (purines and pyrimidines) does not work (Orgel, 2004). The prebiotic synthesis of purine ribonucleotides is still unclear, yet recently a breakthrough has been made with regard to the synthesis of pyrimidine ribonucleotide monomers (which incorporate cytosine and uracil). It now appears in principle to be solved, in a completely unexpected manner. ...”
-and it then goes on to explain how.
Here are two more extracts:
“...The group of David Deamer has shown that the synthesis of RNA-like polymers can even occur from non-activated mononucleotides within phospholipids vesicles, due to the chemical potential of fluctuating anhydrous and hydrated conditions, with heat providing activation energy during rehydration (Rajamani et al. 2008). Such conditions could have existed around hot springs on the prebiotic Earth. The lipids also provide a structurally organizing microenvironment that imposes order on mononucleotides. In this experimental setup, oligomers of up to 100 nucleotides can be formed non-enzymatically. It remains to be seen if prebiotically plausible fatty acid vesicles could have the same effect on RNA synthesis (with this a self-replicating RNA molecule would also have been pre-packaged for further evolution, cf. below). Effective polymerization of monomers that are activated might be aided by a structurally organizing microenvironment within vesicles as well. ...”
“...Extrapolating from all the above data, inside fatty-acid vesicles the first self-replicating RNA molecule could have started copying itself. During copying, various things would have been possible. High-fidelity copies would have yielded the same self-replicating molecule. Copies with errors would mostly have resulted in RNA that was non-functional, but in a minority of cases, they could have yielded RNA that copied itself faster. It has been shown (Chen et al. 2004, see also news article) that RNA/vesicle systems that contain more genetic material (which would have resulted from faster RNA replication) develop more internal tension than neighboring vesicles that do not contain as much RNA, and draw membrane material from them. Importantly, this would have allowed for natural selection of vesicles by competition even in the absence of the ability to synthesize their own membrane components and therefore to directly control their own growth. Thus, for the first time, a system would have had the ability to undergo Darwinian evolution by natural selection acting on variation. This would have been a new and crucial emergent property arising at the transition from non-life to life. ...”
I have to admit I haven't read all of it yet as it's a rather long article but my overwhelming impression is they really have, surprisingly, either got the worst if it pretty much worked out or at least they soon will have.
http://www.talkorigins.org/faqs/abioprob/originoflife.html#RNAworld
it starts of with what I already knew:
“...Even the simplest currently living cells contain hundreds of proteins most of which are essential to their functioning. Yet such complexity cannot have stood at the origin of life. Based on research in the field it is proposed here how, once a self-replicating genetic molecule existed, life might have started and gradual evolution of complexity was made possible ...”
in other words, the first life required none of the complexity of modern life.
“...Later research had cast doubt on the existence of a reducing atmosphere, and suggested a neutral atmosphere instead – see also (Chyba 2005), the accompanying article to Tian et al. (see below).
However, new calculations indicate that hydrogen escaped from the early atmosphere at a much slower rate than previously thought, yielding an atmosphere where hydrogen was a major component (about 30 😵 and which was therefore highly reducing (Tian et al. 2005 , see also press release). ...”
the reason why the above is relevant is because a reducing atmosphere favours the right kind on chemistry for abiogenesis.
“...For a long time the synthesis of RNA monomers under prebiotic conditions appeared to be a fundamental problem since the condensation of sugar (ribose) and nucleobase (purines and pyrimidines) does not work (Orgel, 2004). The prebiotic synthesis of purine ribonucleotides is still unclear, yet recently a breakthrough has been made with regard to the synthesis of pyrimidine ribonucleotide monomers (which incorporate cytosine and uracil). It now appears in principle to be solved, in a completely unexpected manner. ...”
-and it then goes on to explain how.
Here are two more extracts:
“...The group of David Deamer has shown that the synthesis of RNA-like polymers can even occur from non-activated mononucleotides within phospholipids vesicles, due to the chemical potential of fluctuating anhydrous and hydrated conditions, with heat providing activation energy during rehydration (Rajamani et al. 2008). Such conditions could have existed around hot springs on the prebiotic Earth. The lipids also provide a structurally organizing microenvironment that imposes order on mononucleotides. In this experimental setup, oligomers of up to 100 nucleotides can be formed non-enzymatically. It remains to be seen if prebiotically plausible fatty acid vesicles could have the same effect on RNA synthesis (with this a self-replicating RNA molecule would also have been pre-packaged for further evolution, cf. below). Effective polymerization of monomers that are activated might be aided by a structurally organizing microenvironment within vesicles as well. ...”
“...Extrapolating from all the above data, inside fatty-acid vesicles the first self-replicating RNA molecule could have started copying itself. During copying, various things would have been possible. High-fidelity copies would have yielded the same self-replicating molecule. Copies with errors would mostly have resulted in RNA that was non-functional, but in a minority of cases, they could have yielded RNA that copied itself faster. It has been shown (Chen et al. 2004, see also news article) that RNA/vesicle systems that contain more genetic material (which would have resulted from faster RNA replication) develop more internal tension than neighboring vesicles that do not contain as much RNA, and draw membrane material from them. Importantly, this would have allowed for natural selection of vesicles by competition even in the absence of the ability to synthesize their own membrane components and therefore to directly control their own growth. Thus, for the first time, a system would have had the ability to undergo Darwinian evolution by natural selection acting on variation. This would have been a new and crucial emergent property arising at the transition from non-life to life. ...”
I have to admit I haven't read all of it yet as it's a rather long article but my overwhelming impression is they really have, surprisingly, either got the worst if it pretty much worked out or at least they soon will have.