Chemistry of Life and the Role of Temperature

[Turtle]

In general the discussions hypothesizing the requirements for originating life abiotically incorporate a warm environment. The warm shallow sea, or perhaps the hot springs on dry land or black smokers under the seas.
Somehow tonight however I stumbled onto some old report from NASA ( I think I Googled "electrical conductivity of water ice") that took me a bit by surprise.
Makes the promise of finding life on some of our gas giant's moons look more promising.
I have yet to read it all, but here's a tasty quote & the link to the entire treatise:

Originally Posted by NASA.gov

...It has been observed that since the temperature coefficients of certain destructive decomposition reactions that would tend to inhibit the abiotic [62] formation of RNA and DNA are quite large, low temperatures would have been advantageous and, in general, the lower the better (Miller and Orgel, 1974). It is of interest therefore to examine the properties of clay-water interfaces at low temperatures from the point of view of their possible involvement in chemical reactions important in abiotic syntheses of chemical precursors to cellular life....

http://history.nasa.gov/CP-2156/ch1.4.htm

[ronthepon]

Nice article.

[HydrogenBond]

I can see life forming with a combination of hot/cool and high and low UV. At the surface of the water where temperature and UV is high we get the conditions for the formation of energetic molecules and/or radicals. These then sink or diffuse to lower levels in the water where the temperatures are cooler and the affect of UV is lower, allowing stable biochems to form. There may even have been a sweet spot at intermediate water depths where limited UV and mild water temperature allows a optimum balance for small chemical formation and protein, DNA and RNA polymerizations.

[Eclogite]

In relation to clays you should examine the work of Cairns-Smith at the University of Glasgow, if you are not already familiar with it. He believes the first life, i.e. self replicating, chemical mix, subject to inheritance and natural selection, consisted of clays. These then acted as templates on which RNA was assembled. The latter proved fitter, and so took up the baton of evolution, as it were.

[Turtle]

Originally Posted by Eclogite

In relation to clays you should examine the work of Cairns-Smith at the University of Glasgow, if you are not already familiar with it. He believes the first life, i.e. self replicating, chemical mix, subject to inheritance and natural selection, consisted of clays. These then acted as templates on which RNA was assembled. The latter proved fitter, and so took up the baton of evolution, as it were.

Thanks E; his work is new to me. Elements of this may stick to the low-temp hypothesis. Here is an article & quote on Cairns-Smith's work:

http://en.wikipedia.org/wiki/Graham_Cairns-Smith

Originally Posted by wicky

Despite its frequent citation as a useful model of the kind of process that might have been involved in the prehistory of DNA, the 'clay theory' of abiogenesis has not been widely accepted.

[HydrogenBond]

I like a simple polymerization theory to form the first DNA or RNA. In other words, DNA and RNA are composed of monomer units, i.e, pentose sugar, phophate and a base. All that would be needed is a catalyst to attach the phosphate moiety to a sugar moiety, maybe clays, and the railroad cars (monomers) will hook up into a train (polymer). The first DNA would be nonspecific, but would get the ball rolling. All the enzymatic complexity to make DNA, we see today, is needed for specificity not just for polymerization.

[HydrogenBond]

If DNA was to take over as a template for polymerization, with only moderate specificity (slightly more complicated polymerization where DNA becomes the hydrogen bonding surface for semi-specific polymerization), one thing that would need to happen is that the DNA double helix would need to become separated.

What holds the DNA double helix together are hydrogen bonds. To break the hydrogen bonds several simple things could work. The easiest is hot water and a little bit of mineral base. The hot water may also favor the polymerization since the formation of DNA polymers is endothermic.

[Turtle]

Originally Posted by HydrogenBond

What holds the DNA double helix together are hydrogen bonds. To break the hydrogen bonds several simple things could work. The easiest is hot water and a little bit of mineral base.

The NASA study I quoted when starting the thread says otherwise.

Originally Posted by NASA

Originally Posted by NASA.gov
...It has been observed that since the temperature coefficients of certain destructive decomposition reactions that would tend to inhibit the abiotic [62] formation of RNA and DNA are quite large, low temperatures would have been advantageous and, in general, the lower the better (Miller and Orgel, 1974).

Inasmuch as their statements come as the result of actual experimentation , I have to give them more trust. Why not assume it true, (even if you don't believe it) & design experiments to support it; you may actually end up affirming your belief by a contradictory result or changing your mind by an affirmative result.

[quatumrulesoverall]

Nice article, I wanna add on that as temperature plays a very important role in reaction as it changes the rate of forward and backward reaction, and hence change the euilibrium position