RNA world vs. Iron-Sulfer world theory

[cameron marical]

I was wondering whats more popular, the Iron-Sulfur world theory, or the RNA world theory. I cant really make a stand yet, because I do not know enough about either one yet, but I want to hear the pros and cons of both through peoples thoughts. Maybe spark some good debates too.

[Psycho]

I don't think they are actually competing, Iron-Sulphur clusters are present in many proteins. As well as many organism using them as anaerobic energy sources in electron transport systems as terminal electron acceptors as well as in the cytochromes allowing the change in redox potential within them.

 

The RNA world hypothesis says that RNA which can self-splice and create enzymes from itself is a completely different hypothesis on what the current state of life might have evolved from.

[cameron marical]

From what I read about the Iron-Sulfur world theory, It is the idea of a metabolism first rather than RNA first, I was not focusing on Iron-Sulfur clusters{although, thanks for the info}. From what I understand, they are both hypothesis's for how the current state of life might have evolved from.

 

 

http://en.wikipedia.org/wiki/Iron-sulfur_world_theory

 

http://en.wikipedia.org/wiki/RNA_world_hypothesis

[Psycho]

From what I read about the Iron-Sulfur world theory, It is the idea of a metabolism first rather than RNA first, I was not focusing on Iron-Sulfur clusters{although, thanks for the info}. From what I understand, they are both hypothesis's for how the current state of life might have evolved from.

 

 

http://en.wikipedia.org/wiki/Iron-sulfur_world_theory

 

http://en.wikipedia.org/wiki/RNA_world_hypothesis

Iron and sulphur are used in metabolism now, as is RNA, but they aren't conflicting theories.

[cameron marical]

I am not talking about our present day metabolism, I am talking about the two hypotheses that Guntar Watchterschauser and Walter Gilbert proposed. One, wich suggests that life started with metabolism first, the other suggesting that with life, RNA started first.

 

Please, look at the links.

[granpa]

fire reproduces but cannot evolve and therefore isnt 'alive'. strictly speaking metabolism would be the same so I would have to say that 'life' itself began with rna.

 

but yes I do believe that there may have been a kind of 'fire' burning on the early earth which may have been the beginning of our metabolism.

[Moontanman]

metabolism-clay life-trashbag-RNA world-DNA is my take on the progression of life.....

 

or maybe metablism-clay life-RNA-trashbag, I'll have to go back and read a couple of the newest books again to be sure, my old man memory is less than perfect these days

 

Peter Wards "life we do not know it" is a good one

[granpa]

the biggest issue with the rna world is how to make the nucleotides. people invent elaborate chemisry's to try to explain it. I think whats needed is a simple chemistry that produces all kinds of organic molecules and then some elaborate process that seperates out just the molecules that have just the right properties that are needed for nucleotides.

 

thats my take on it.

[insane_alien]

granpa, the chemistry for making RNA isn't all that elaborate. amino acids form on their own if you have some nitrates and such in the water along with some dissolved carbon, stick em in with each other and there will be poly peptide formation and so on.

 

its sort of like saying counting is elaborate because there are so many stages to it, first you have to count 1, then you have to count 2, then you have to count 3. all pretty simple there but wait till you get to 100 wow thats elaborate.

 

and whats more, 99% of the 'elaborate' chemistry happens when you recreate the conditions of early earth and leave it alone for a couple of months. the only step we have yet to see is the part we suspect requires a larger volume(like an ocean) to have a reasonable chance of occuring. the actual polymerization to a useful strand of RNA and some proteins.

[cameron marical]

Does abiogenesis have a stance on either one, or is it nuetral in a way?

[granpa]

http://www.ncbi.nlm.nih.gov/pubmed/11296526?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/6462692?dopt=AbstractPlus

 

Many accounts of the origin of life assume that the spontaneous synthesis of a self-replicating nucleic acid could take place readily. Serious chemical obstacles exist, however, which make such an event extremely improbable. Prebiotic syntheses of adenine from HCN, of D,L-ribose from adenosine, and of adenosine from adenine and D-ribose have in fact been demonstrated. However these procedures use pure starting materials, afford poor yields, and are run under conditions which are not compatible with one another. Any nucleic acid components which were formed on the primitive earth would tend to hydrolyze by a number of pathways. Their polymerization would be inhibited by the presence of vast numbers of related substances which would react preferentially with them. It appears likely that nucleic acids were not formed by prebiotic routes, but are later products of evolution.

 

http://gow.epsrc.ac.uk/ViewGrant.aspx?GrantRef=EP/E032753/1

Spectacular advances in structural and molecular biology have added support to the 'RNA world hypothesis', and provide a mandate for chemistry to explain how RNA might have been generated prebiotically on the early Earth. The 'molecular biologist's dream' - a phrase introduced by Jerry Joyce and Leslie Orgel - refers to a scenario in which prebiotic chemistry somehow furnishes pools of enantiopure beta-D-ribonucleosides. There is still a long way to go from such nucleosides to RNA, but the experimental demonstration of in vitro RNA evolution suggests that once RNA has arisen, its evolution might be relatively easy. Several groups worldwide are investigating the evolution of simple RNA polymerase ribozymes, and the general impression is that, although this is difficult, there is reason for optimism. There has, however, been little optimism about the chances of a prebiotic synthesis of beta-D-ribonucleosides and the corresponding nucleotides, indeed the mood has been distinctly pessimistic. This is because of the intractable mixtures that result from most attempts to make nucleosides using conditions that simulate the chemistry of the early Earth - the 'prebiotic chemist's nightmare'.

 

http://en.wikipedia.org/wiki/Talk:RNA_world_hypothesis#Chemical_objections

Edited June 28, 2009 by granpa