New Chemical Scenario For How Life Emerged On Earth

UniSci ^ | 20 June 2002

[AndrewC]

That the macro-molecular building blocks of life could have formed naturally

Apart from not slamming any gaps shut(Another gap slams shut. ) how is this any different than the Miller-Urey experiment?

[Bush2000]

There was an experiment back in the 50s by Miller-Haldane which illustrated the possibility for amino acids to be formed by lightning breaking bonds within gases in a primitive earth atomosphere. I replicated it back in high school so I've verified that much. But other posters are quite right that it's unknown how amino acids spontaneously formed themselves into peptide chains and, then, into primitive cells. This is the key to understanding our biological growth. In my personal opinion, "science" in this regard is on rather shaky ground. That's not to say that it couldn't happen -- but it's extremely difficult to prove conclusively.

You know, there is room in the theory of evolution for the existence of a Prime Mover -- God, if you will -- that set about a few basic processes and left them to evolve on their own. Darwin did not disprove the existence of God. And recently, there have been moves among physicists to consider the moments immediately prior to the Big Bang -- something that they've been loathe to do previously because almost nothing is known about that time. To paraphrase one of them, "We don't have proof of the existence of God. But to ignore the hypothesis that God may exist and formed the universe prior to the Big Bang is just plain wrong."

[Bush2000]

Apart from not slamming any gaps shut(Another gap slams shut. ) how is this any different than the Miller-Urey experiment?

I was wondering this myself. (And as a footnote, it appears that we both haven't given credit where credit is due: It's "Miller-Haldane-Urey")

[Junior]

The assumed constituents of the atmosphere are different and more accurately reflect what is known of the atmosphere of the time, and the mechanism constructing the peptides is different. Also, I don't think the latest experiment required electrical input.

[VadeRetro]

And they seem to be describing polymerization in there. That gives another method besides comet impacts.

[PatrickHenry]

Here's something I posted about a week ago, in response to a creationist who raised the hoary old argument about how the odds are against the appearance of the first living cell:

This notion [the extreme unlikelihood of the accidental occurance of life. Arguably, it is an event which is mathematically impossible] is like the Terminator. It just won't die, no matter how many times you shoot it, blow it up, crush it, burn it, etc., it just keeps on coming ...

You seem to have this notion of a strand of complicated DNA just popping into existence out of random atoms scattered around the universe, but chemistry doesn't work like that. You start with an ocean full of organic compounds which form naturally (and which can be demonstrated to do so in the lab). Make that several oceans, because earth has lots of ocean. Carbon forms organic compounds very easily. You can't really prevent it. Carbon atoms are very promiscuous. They can naturally form long, complicated chains of organic molecules. Most of those chains are worthless, but you've got oceans full of this stuff, trillions of organic molecules drifting around, and you've got hundreds of millions of years to play with. That's billions and billions of potential combinations and re-combinations going on all the time, for millions and millions of years. Some compounds may have drifted in from comets, as they form so readily that we find them off the earth as well as here at home. It just takes one time that one of those already complicated strands combines with another and blunders into the configuration required to be a self-replicator. It doesn't pop into existence from scratch; it's assembled from pre-existing components (this is the point so often missing in the "life from non-life is impossible" math models). Then, before long, you've got oceans of self-replicating molecules. They bubble and boil and combine and re-combine for millions of years. It's not really inevitable that you'll get living material out of this organic brew. But it's certainly not impossible. And here we are. Ta-da!

[AndrewC]

The assumed constituents of the atmosphere are different and more accurately reflect what is known of the atmosphere of the time, and the mechanism constructing the peptides is different. Also, I don't think the latest experiment required electrical input

Assumed and accurate seem to be contradictory in this usage. The atmosphere is different, and in fact was apparently not used in the experiment. The experiment was designed and performed to achieve peptide synthesis using amino acids and nitric oxides. Then modeling was used to allow the final announcement. What do you think happens in modeling?

What results did they get?

• Only a few of all the possible peptide sequences were formed, demonstrating that the primary pump should be able to select particular peptide sequences. (or that only limited synthesis is possible)

[Junior]

Assumed and accurate seem to be contradictory in this usage.

...and more accurately reflect what is known...

"Accurate" and "more accurately reflect what is known" are not synonymous. You're not the only one who can play the lawyer game...

[FourtySeven]

Welp, so much for having never seen evolution in the laboratory.

Good post!

[AndrewC]

Play lawyer all you want. You didn't address anything. Seem requires no answer.

[Wm Bach]

And who knows where the swami's info comes from?

I'll field this one - Less evolved swamis.

[Viva Le Dissention]

Although not *overly* religious, having been the product of a fine Jesuit Education, I have to ally myself with the camp of the creationists.

In a brilliant series of essays, Aquinas (re)presented the "First Mover" argument, which is a good argument by my analysis. I've yet to meet anyone who can refute it, but you are, of course, welcome to try.

1. Things are in motion.

2. In order for an object to be in motion, it has to be set into motion by another [object or force.]

3. The chain of motion cannot be infinite.

-----------------------

Since the chain of motion cannot be infinite, and all objects must be set into motion by another (Newton's 2nd law), there MUST be a First Mover.

That's a simple but powerful argument for the existence of God. Then again, that could just be the Jesuits talking.

[general_re]

Bwahahaha...too funny...

[PatrickHenry]

Since the chain of motion cannot be infinite, and all objects must be set into motion by another (Newton's 2nd law), there MUST be a First Mover.

That's a simple but powerful argument for the existence of God. Then again, that could just be the Jesuits talking.

Several points. First, if there really were a literal proof of god, no one would be concerned with faith. But we are. Second, the existence of a prime mover is not necessarily the same thing as the existence of god. Third, there have been several refutations of Aquinas' arguments over the centuries.

Here's just one website dealing with errors in the proofs of Aquinas. There are several such sites around, and this may not be the best, but it's the first I located. Look around, you may be surprised. HERE.

[AndrewC]

I was wondering this myself.

A little searching on carboxyanhydrides produced this link. It might be an indication of where some of the particulars of this "molecular engine" originated.(also might indicate some of the design)

Surface-Grafted Poly(L-glutamates): Design, Synthesis and Properties

Polymerization of NCAs can be initiated by primary amines. By immobilizing an appropriate initiator on the surface of a solid substrate (glass, quartz, silicon, aluminum etc.), it is possible to grow polypeptide chains directly from the surface (the 'grafting from' approach) thus leading to a relatively high grafting density and reaction-induced polar order (see scheme 2).

Scheme 2 Initiation of an N-carboxyanhydride (2) polymerization by an immobilized primary amine

 

An interesting feature of this ring-opening polymerization is that it follows the so-called 'living' amine mechanism. The primary amine that is present at the end of a grafted polypeptide chain can initiate the polymerization of a second NCA monomer. This offers the possibility to synthesize block copolypeptides or even multiblock polypeptides.

Another advantage of this polymer system is the possibility to tune the properties of the polypeptide by means of side group chemistry. Direct or indirect esterification of L-glutamic acid or transesterification of already formed poly(L-glutamates) enables the synthesis of polyglutamates with long alkyl side chains, chromophores, liquid crystalline groups etc.

To illustrate the great potential of poly(L-glutamates), take a look at some interesting properties of poly(g-benzyl-L-glutamate) (PBLG):

· excellent solubility in organic solvents like THF, DMF and chloroform;

· very stable rigid rod-like a-helical conformation;

· thermally stable up to 160 °C;

· shows cholesteric lyotropic liquid crystalline behaviour;

· shows NLO-activity;

· can be used as a biomaterial in pharmaceutical applications.