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Author Topic:   The Recurrent Problem of Chirality
Evopeach
Member (Idle past 5164 days)
Posts: 224
From: Stroud, OK USA
Joined: 08-03-2005


Message 1 of 81 (285281)
02-09-2006 4:49 PM


Life as we know it, uses twenty amino acids to form the molecules that enable life to operate biologically, whether plant or animal, macroscopic or microscopic.

These forms are except for one extant in nature in two, three-dimensional forms called levo and dextro, left and right handed as in a glove analogy.

Now when these two forms make their way into biological molecules used in life they appear in completely separated form and not in mixed forms of both types.

Life cannnot begin or proceed using racemic mixtures of the two forms for life molecules.

Now the evolution of the first replicator pre-rna to rna to dna and the first cell could not have happened without this separation of otherwise identical forms of the molecules.

More importantly perhaps is the fact that it is only the three dimensional aspect of the molecules and their coiled shape in the double helix of the DNA that enables them to store the information contained in the "genetic code" sequences non-linearly rather than linearly in two dimensions. In fact it is impossible to store the information in three dimensions in the double helix form using racemic mixtures of molecules.. it simply cannot be done.

The microscopic sized 3-d information storage and retrieval capacity of the DNA molecule critical to the entirity of celluar operations is dependnet on the optical purity of the building block molecules of life.

But since the two forms are chemically identical and have identical entropy states they cannot be separated or distinguished by pure chemistry. There is no entropy or alternately free energy gradient.

Now more than 100 years ago a brilliant European chemist discovered that if he could take a molecular extract from the deadly nightshade plant the l-brusine built by the genetic code of deadly nightshade in its cell and use it in a carefully controlled experiment with the tetrahedral molecule alanine in both L& D forms and centrifuge the mixture he could obtain a separation because the l-form salt would percipitate out as a pure crystal (valanine) while the d form stayed in solution as a brown oily substance.

But it was only possible by using the dna information in the deadly nightshade which makes the l-brusine as part of its celluar operations that this optically pure separation of the alinine forms was possible.

But of course never not ever nanda did such a possibility exist in the pre-rna rna world so how did the separation occur which is absolutly required for 3-d data storage on the DNA molecule... not one feasable theory or experiemnt has ever been been proposed much less performed and demonstrated.

Another demonstration of intelligent design.. inexplicable by evolutionary theory.


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AdminWounded
Inactive Member


Message 2 of 81 (285326)
02-09-2006 7:36 PM
Reply to: Message 1 by Evopeach
02-09-2006 4:49 PM


You have brought this almost exact same argument up before.

Now as then you seem to be confused between amino acids and nucleic acids, and now as then you provide no useful reference to the experiments on the isolation of optical isomers of alanine. Was the experimenter Marckwald, who was at least one of the first to use Brusine? was it Pasteur who observed the seperation of L- and D- forms of tartaric acid?

I think that without some references to support your numerous assertions, or some novel line of argumentation, this doesn't merit rehashing.

TTFN,

AW


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AdminWounded
Inactive Member


Message 3 of 81 (285526)
02-10-2006 12:18 PM
Reply to: Message 2 by AdminWounded
02-09-2006 7:36 PM


Given the ongoing discussions inkorrekt is having on this topic I am promoting this PNT to help alleviate derailment of other threads.

TTFN,

AW


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AdminWounded
Inactive Member


Message 4 of 81 (285527)
02-10-2006 12:18 PM


Thread moved here from the Proposed New Topics forum.

  
jar
Member
Posts: 32663
From: Texas!!
Joined: 04-20-2004
Member Rating: 1.8


Message 5 of 81 (285572)
02-10-2006 1:17 PM
Reply to: Message 1 by Evopeach
02-09-2006 4:49 PM


on sources of Chirality
There are actually quite a few well known theories on how Chirality developed, so there is no great mystery there. No one is sure about which method or combination of methods led to the current life forms, but the posibility of a natural cause is certainly there.

Here are a few references on potential methods.

Purdue scientists discover why we’re all lefties deep down

Origin of chirality in biological molecules

Rocks May Have Given a Hand to Life

the Weak Force as cause

something to get all stirred up about

just plain chemistry

There are many other such references but these should help you get started.


Aslan is not a Tame Lion

This message is a reply to:
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Replies to this message:
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Evopeach
Member (Idle past 5164 days)
Posts: 224
From: Stroud, OK USA
Joined: 08-03-2005


Message 6 of 81 (285690)
02-10-2006 5:05 PM
Reply to: Message 5 by jar
02-10-2006 1:17 PM


Re: on sources of Chirality
Purdue article is typically silly and humerous. The molecule in question is not even necessary for the mammalian diet since it can be synthesized easily within the body from other molecules. That would selectively make it a late comer not a dominate first comer.

The verbage in the paper is replete with the typical meybe, we imagine, could have been phrases typical of the evolutionary communities vain imaginings. LOL

Not a scintilla of text is devoted as to why or how one molecules predisposition to bond with lefthanded molecules arose is given or how that could possibly influence what other molecules predisposition might be particularly whrn the so called dominate leader doesn't even apprear in the great majority of proteins and enzymes.

Neither does the paper address how among the 50/50 mixture of racemates across all the amino acids present in any abiotic sea and there are many how only twenty are exclusively used in life and of course only the optically pure separated forms are used.

I believe I'll pass on the spaceman from planet zabot theory.. only to say that when these sci-fi theories are proposed its out of desperation because no terrestrial theories such as one are anything other than laughable.

Rock terrraces show 10% bias to lefties... well is 10% the same as 99.99999...999% separation because thats whats required for polypeptides in life molecules. And even if true that lefties like terraces.. why one cannot even imagine ... the end result requires the chance formation pulr lefty molecules when there were plenty of righties absolutely therodynamically indistinguishable handy on the same terrace.... 40% of the molecules were right handed.. maybe they were ugly. LOL

"parity-violating energy differences" could be amplified kinetically in the pre-biotic soup to preferentially select today's L-amino acid/D-sugar biochemistry over D-amino acid/L-sugar "mirror life".
If this newspeak can be interpreted to make any sense.. lets hear it.
Of course any so called energy difference at the QM level would need be amplified say by a factor of a trillion orders of magnitude. But I geuss the magnifier got lost because today no experiment can demonstrate its operation. Yep those 50/50 racemic mixtures just refuse to be amplified in the old soup and continue to form useless racemic peptides.

Although we do not fully understand the origin of the chart of intermediary metabolism,our present knowledge points to a logic which I believe we will one day understand as we nowcomprehend structures like the periodic table of the elements.

One day we will all be engulfed in peace and happiness blah blah blah.

The problem of selecting twenty amino acids from many and using only one form predominately remains as inexplicable as 100 years ago.

Separation always requires the genetic machinery codes and instructions that are built in the same optically pure fashion.


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 Message 5 by jar, posted 02-10-2006 1:17 PM jar has responded

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jar
Member
Posts: 32663
From: Texas!!
Joined: 04-20-2004
Member Rating: 1.8


Message 7 of 81 (285692)
02-10-2006 5:19 PM
Reply to: Message 6 by Evopeach
02-10-2006 5:05 PM


Re: on sources of Chirality
Argument from incredulity won't work over here on the science side.

No one objects to any belief you might personally hold. You are free to believe 2 + 2 = 5 all day long.

However, in your OP you present Chirality as a poblem. In response I present not one, not two, not three, not four, not five but six different all natural methods that would account for what we see.

QED, there is no Recurrent Problem of Chirality, no need for some ID mechanism.


Aslan is not a Tame Lion

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Evopeach
Member (Idle past 5164 days)
Posts: 224
From: Stroud, OK USA
Joined: 08-03-2005


Message 8 of 81 (285693)
02-10-2006 5:25 PM
Reply to: Message 7 by jar
02-10-2006 5:19 PM


Re: on sources of Chirality
Nice try that argument from credulity..

Actually its an argument from 100 years of abject failure to resolve a major problem which no one has even come close to explaining by evolutionary mechanisms.

The examples you give are five mutually exclusive diametrically opposed pseudo explanations given mostly out of desperation.

They left out the Von Damian Chariot of the Gods theory.

These just so stories without a scintilla of evidence doesn't fly with we true intellects.

Back to the drawing board ... laughable.


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Belfry
Member (Idle past 3636 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 9 of 81 (285767)
02-10-2006 9:48 PM
Reply to: Message 8 by Evopeach
02-10-2006 5:25 PM


Re: on sources of Chirality
Evopeach, do you know what an argument from incredulity is? Your latest post is a classic example.

Scientists don't claim to know for certain how chirality came to be. What jar has done is to refute your primary assertion, namely:

Evopeach writes:

Another demonstration of intelligent design.. inexplicable by evolutionary theory.

We do have plausible explanations within evolutionary theory. We don't know whether any of them are correct or not. But, your claim that they are "inexplicable" is falsified. Unexplained does not equal inexplicable.


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sidelined
Member (Idle past 4458 days)
Posts: 3435
From: Edmonton Alberta Canada
Joined: 08-30-2003


Message 10 of 81 (285819)
02-11-2006 9:21 AM
Reply to: Message 1 by Evopeach
02-09-2006 4:49 PM


ID is a hollow shell game.
Evopeach

Another demonstration of intelligent design.. inexplicable by evolutionary theory

You fail to establish here how the intelligent design is suffient and necessary for the amino acids chirality and why evolution will never be capable of explaining this.

Regardless, this is simply not the case.There are models which are capable of giving clues to the origin though none fully developed simce the standards required by science are, unlike the intelligent design hypothesis,subject to rigorous investigation and experimental verification.

Allow me to reference but 2 articles to show the possibilities for chirality on earth.Here is the first.
http://www.ast.cam.ac.uk/AAO/local/www/jab/astrobiology/chirality.html

Chirality and the Origin of Life
The origin of the homochirality of biological molecules (the use in living organisms of only left-handed or L-amino acids and right-handed or D-sugars) has puzzled scientists since the chirality of molecules was discovered by Louis Pasteur more than 150 years ago. Recently it has been discovered that an excess of L-amino acids is present in the Murchison and Murray meteorites indicating that a preference for L-amino acids existed in solar system material before there was life on Earth. This supports an idea, first proposed by Rubenstein et al. (1983, Nature 306, 118), for an extraterrestrial origin for homochirality.

In this model the action of circular polarized light on interstellar chiral molecules introduced a left handed excess into molecules in the material from which the solar system formed. Some of this organic material then finds its way onto Earth via impacts of comets, meteorites and dust particles during the heavy bombardment phase in the first few hundred million years of the solar system. These molecules were then part of the prebiotic material available for the origin of life, and tipped the scales for life to develop with L-amino acids and D-sugars.

Rubenstein et al. originally proposed that synchrotron radiation from neutron stars in supernova remnants would be a suitable source of the required UV circularly polarized light. However, this interpretation is not supported by theory or observation which show that the circular polarization of these sources is very low. New observations with the Anglo-Australian Telescope (above) have shown suprisingly high circular polarizations (the red and white regions in the image) in the infrared light from reflection nebulae in the star forming regions Orion OMC1 (a region in the Orion nebula M42) and NGC 6334. Although we can only observe these regions at infrared wavelengths which can penetrate the thick dust clouds in which they are embedded, it is predicted that circular polarization should also be present at the ultraviolet wavelengths needed for asymmetric photolysis of molecules such as amino acids. If our own solar system formed in such a region of high circular polarization, it could have led to the excess of L-amino acids which we see in meteorites and to the homochirality of biological molecules. It is possible that without such a process operating it would not be possible for life to start. This may have implications for the frequency of occurrence of life in the universe.

And the second
http://www.sciencenews.org/articles/20010505/fob1.asp

Rocks May Have Given a Hand to Life
Jessica Gorman

A long-standing mystery about the origin of life has a new possible solution.

The puzzle is that amino acids, the constituents of proteins, occur in two chemically identical forms that have structures mirroring each other like two gloves. Most chemical processes yield left- and right-handed amino acids in equal amounts yet life forms contain left-handed amino acids almost exclusively. New findings show that a mineral common on the ancient Earth might have segregated the mirror-image versions.

Much speculation has focused on extraterrestrial influences behind early life. Some scientists suggest that extra left-handed amino acids arrived on meteorites as life was emerging on Earth (SN: 2/22/97, p. 118). In another theory, Earth formed from dust harboring a primordial excess of left-handed amino acids.

A yellowish calcite crystal.
Rob Lavinsky

Researchers in Washington, D.C., now report that calcium carbonate, or calcite, can adsorb an excess of left-handed amino acids onto some of its crystal faces and of right-handed amino acids on other faces. Robert M. Hazen and Timothy R. Filley of the Carnegie Institution of Washington and Glenn A. Goodfriend of George Washington University report their results in the May 8 Proceedings of the National Academy of Sciences.

"It is very exciting," says Max Bernstein of NASA's Ames Research Center and the SETI (Search for Extraterrestrial Intelligence) Institute, both in Mountain View, Calif. "Such results provide a plausible scenario by which . . . amino acids could be separated from their mirror images, potentially solving a vexing problem of prebiotic chemistry."

In their analysis, the scientists focused on calcite because it was widely present on the early Earth and is compatible with biological molecules. For instance, it's the primary ingredient of sea shells.

The researchers placed each of four fist-size calcite crystals in a 50-50 solution of right- and left-handed aspartic acid, an amino acid. Two of the crystals had super-smooth surfaces, and two had microscopic terraces. The scientists found that the terraced crystals ended up with a 10 percent excess of right-handed amino acids on one type of face and a similar excess of left-handed amino acids on another. The smooth-faced crystals tended not to differentiate between the mirror-image forms of aspartic acid.

Hazen speculates that billions of years ago, amino acids might have lined up on crystals' terraces. They could have then combined into the first all-lefty peptides, or short protein segments.

The calcite results are "of special significance for origin-of-life researchers," says Noam Lahav of the Hebrew University in Jerusalem. But he cautions that the findings still do not point to a chemical mechanism by which southpaw amino acids overtook their right-handed siblings as life emerged.

John Cronin of Arizona State University in Tempe also remains puzzled. Since both the mirror forms become concentrated on crystal faces, "it would be necessary for life to have originated from a particular spatially isolated crystal surface, which seems rather improbable," he says.

Hazen suspects that, in fact, that's what happened. The left-handed amino acids in one place got the edge, he speculates, because by pure chance, these lefties bonded into peptides capable of self-replication.

References:

Hazen, R.M., T.R. Filley, and G.A. Goodfriend. 2001. Selective adsorption of L- and D-amino acids on calcite: Implications for biochemical homochirality. Proceedings of the National Academy of Sciences 98(May 8):5487.

Further Readings:

Peterson, I. 1997. Left-handed excess in meteorite molecules. Science News 151(Feb. 22):118.

Sources:

Max Bernstein
Astrophysics Branch
Mail Stop 245-6
NASA Ames Research Center
Moffett Field, CA 94035-1000

John R. Cronin
Department of Chemistry and Biochemistry
Arizona State University
Tempe, AZ 85287-1604

Robert M. Hazen
Geophysical Laboratory
5251 Broad Branch Road, N.W.
Washington, DC 20015-1305

Noam Lahav
Faculty of Agriculture
Hebrew University of Jerusalem
P.O. Box 12
Rehovot 76100
Israel

Your turn now evopeach. How does the intelligent design hypothesis explain chirality?It cannot since it merely heaps the problem onto a chimera used by those close minded individuals who refuse to investigate properly the mysteries of the world with due care and honesty.

ID holds no explanatory power because it is not an explanation but a shell game.You cannot assuage hunger by snapping at empty air with the hopes of gaining sustenance.

This message has been edited by sidelined, Sat, 2006-02-11 07:23 AM


But I realize now that these people were not in science; they didn’t understand it. They didn’t understand technology; they didn’t understand their time. R.P. Feynman

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Brad McFall
Member (Idle past 3583 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 11 of 81 (285837)
02-11-2006 12:06 PM
Reply to: Message 1 by Evopeach
02-09-2006 4:49 PM


towards a valid form of discussion

Click to enlarge

I am working on putting these four sided figures (Statistically) within para's figure ONE by being composed of Weyl's differences of 1-D symmetry types such that there would exist an explanation of Parasomonium's figure 2 interms of a closed topological space dependent on different 1-D symmetry components. If this works then the two added figures will still not decide if the difference of left and right is due to God's existence or simply the tracing of the curve on shapes of bilateral symmetry. I do not know if the form is valid itself yet, but if I can verify that I suspect the pure math will have something to indicate relative to proposals on chirality.
(also):
I havent listened to
www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=19&t=246&m=81#81 -->www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=19&t=246&m=81#81">http://www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=19&t=246&m=81#81
(it is much too loud in the Coffe shop just now and I did not bring head phones (sorry Moose I missed the post))
on structuralism but a while ago I had to think a bit about LACAN
http://www.colorado.edu/English/ENGL2012Klages/lacan.html
and I realize this is not the issue though it might have been back in the 60s before the lack of use of thom's catastrophe theory in the 70s OCCURED. I also need to work out my response to Percy in detail.

I did hear them say there is "no transcendental signifed", this would be wrong(even if technically correct( it would be based on a mistransference of univocal science language and plurivocal real language) if my form is valid AND predicts phenomena approximating better and better predictions.

This message has been edited by Brad McFall, 02-11-2006 12:08 PM


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sidelined
Member (Idle past 4458 days)
Posts: 3435
From: Edmonton Alberta Canada
Joined: 08-30-2003


Message 12 of 81 (286745)
02-15-2006 1:56 AM
Reply to: Message 1 by Evopeach
02-09-2006 4:49 PM


Evopeach

You intend on posting a rebuttal to post #10 soon?


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Parasomnium
Member (Idle past 1247 days)
Posts: 2191
Joined: 07-15-2003


Message 13 of 81 (286760)
02-15-2006 4:05 AM
Reply to: Message 8 by Evopeach
02-10-2006 5:25 PM


Re: on sources of Chirality
Evopeach writes:

These just so stories without a scintilla of evidence doesn't fly with we true intellecs.

No true intellect would ever produce a sentence like that.


This message is a reply to:
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robinrohan
Inactive Member


Message 14 of 81 (286769)
02-15-2006 5:23 AM
Reply to: Message 13 by Parasomnium
02-15-2006 4:05 AM


Re: on sources of Chirality
No true intellect would ever produce a sentence like that.

Still, pretty impressive, words like "chirality" and such. I looked it up but still am in the dark. Words like that are probably like "please" and "thank you" in Evopeach's circle.


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Parasomnium
Member (Idle past 1247 days)
Posts: 2191
Joined: 07-15-2003


Message 15 of 81 (286777)
02-15-2006 6:04 AM
Reply to: Message 14 by robinrohan
02-15-2006 5:23 AM


Re: on sources of Chirality
O, I think Evopeach is intelligent all right, but when he starts spouting things like that he just deserves a rap on the knuckles, especially if he produces such a linguistic monstrosity saying it.

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