MrBlank1 - 23-8-2015 at 11:57
Greets all,
Just wanted to get a different disciplinary point of view.
I'll skip the preamble if possible (if clarity allows) and just identify my question/subject of issue :
Biologists seem to put a lot of faith in the whole "one-pot-racemic-synth" origin of amino acids, and consequent incorporation of only the L- isomers
into the cellular origins of life (possibly due to Miller-Urey experiments).
Does anyone here also think that to be highly unlikely/improbable?. The whole chirality thing is a big issue with that theory unless I'm totally
missing something.
Just wanted the opinion of chemists regarding the chemistry, coz the biologists seem very evasive when I ask for a "how?".
[Edited on 23-8-2015 by MrBlank1]
aga - 23-8-2015 at 13:31
I have no idea How.
I'm allowed to say that as i have no Vested Interest in the subject.
Professional (Bio)Chemists cannot say that for the opposite reason.
Miller and Urey did some experiments. You can do the same.
As with all things, the results will help you know something that someone else can refute (and they may well be right).
At least you'd have the experiment and data to back up your argument in such a discussion.
The One-Zapped-Pot-Fits-All is highly unlikely in my addled mind.
The main thing is that Urey/Miller wanted to see what happened when you zap a pot of soup of Imagined pre-life sea-solution and an array of amino
acids Were created, which adds something to our knowledge.
Not a conclusive experiment, but definitely adds to the Known.
MrBlank1 - 23-8-2015 at 14:22
You have a valid and relevant point.
One day I'll have my glassware and reagents again, one way or another. Until I know which way I need to go (still waiting), I've just gotta be
patient, push on with the theory, and be thankful for the Millers' and Ureys' of the world. I can't wait to put my hands on glass again, but until
then...
I ask because I wish to be as informed as I can (still without equipment for now) as to the opinion of non-biology students/lecturers, so I
can present some of the possible problems/strengths of both "hydro-thermal vent/soup" and panspermia theories.
I have a fair bit of data on the subject, and it's only for added specificity at the end of a project on an endosymbiont organism in my "evolution
and origin of life" unit at uni. It's only optional, but I'm not happy with presenting just one (problematic?) POV.
It just seemed odd to me that the basic chem/math is so downplayed/not recognized, but it is not unexpected I suppose.
My money has always been on interstellar racemic formation, followed by degradation of the D- isomer amino acids faster than L-, whilst en-route to
us, as substrate on a suitable seed object from outer solar system or further.
In case anyone else is interested in the subject at some stage in the future :
http://xwalk.ca/origin.html
PHILOU Zrealone - 10-9-2015 at 10:19
Some say that:
-reflexion of light upon water surface induces polarized light that may have favoured one chirality over the other.
-some minerals are chiral (random example not linked to primary soup: Na chlorate for example is achiral but on crystalization induces dextrogyre or
levogyre cristals) and may have catalysed one reaction favourising one chirality over the other.
-life is chaotic and as such it could have gone one side or the other, and by a mere chance/hazard one side was chosen and evolved faster becoming
then the strongest attractor of the all living system...feeding on the weakest other chirality.
[Edited on 10-9-2015 by PHILOU Zrealone]
Little_Ghost_again - 10-9-2015 at 10:41
There is a paper I think on here somewhere (or maybe its on my computer), that says the experiment you mention was shown to be slightly out. The
theory they worked on was with a given set of conditions they thought existed at the time, more recently this was show not to be the case (I will go
hunt the paper), however when the new soup was brewed it stilled showed amino acids were possible.
Again the newer experiment is doable at home and dosnt prove much, my dad is a Biologist and he says that there is more than one way to skin a cat. So
while it may well have produced amino acids there were likely more than one thing at play, at present there is little to fully answer the HOW. Time
and again they revise what they think the conditions were at the start, last night I watched horizon that seemed to claim the start was earlier than
we think.
So for me I cnt see anyway to prove how anything happened until we can prove exactly what the conditions were