The Recurrent Problem of Chirality

Yep, I've been wandering through EvC for about the past 8 months.In fact it was Evopeach who led me here about a year ago. He was so fun on Panda's Thumb with his accusations of all evolutionists being "satan worshipping communist sewer pigs" that I Googled his name and found EvC after he was permanently banned from PT.

Hmmm. I kinda like the ring of that. New sig, maybe?

Originally EP had:

quote:

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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.

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When I meant that I did not "believe" it to have been the case that one can infer common descent from a choice of either/or or both as you wrote to Bradcap1.I was trying to point to a thought of my own that may investigate effects of the "similar entropy" of different hands' creating different relations externally during selection that I started to indicate the form of in my first post in the thread. Thus I did not see that choice of one L or D mattered as to Darwin's case for common descent because I would suspect that in the atomic end the glove analogy to Kant's placement in any similar architectonic would not end anaytically where either evopeach or bradcap1 seemed to pre-dictate (as per their posts) it was.I only said "believe" to leave it easier for bradcap1 to respond to me. I could have said, "I think" instead.I did not follow evopeach's other use of argument/debate to which WK was refering.If the anaysis could have been carried to the entropic relations that may differ not per left or right forms but as to relations (say, autocatylses) beyond the "hands'" and this mattered across the scales of levels of organization as I am want to think or believe, in contradistinction to Gould's positioning on the 10 forms of worms at the Cambrian boundary etc then it did not seem necessary to me that Bradcap1 should have criticized Evopeach for his notions of information storage in 3D but only in what he might have meant by "except for one extant in...".I understood that Bradcap1 was likely refering to your correction of the BBCODES but he also might have used you iconically to feel less need to return post. I dont care either way.I am trying to focus on Gould's attempt to split the "standard darwinism" into a 3-legged formation but in doing so I think he let the argument TO common descent have too much room just because he did not want to involve the relation of rotation of the Earth to geographic speciation IN THE BIOLOGICAL portion of his thematization. That was an "external" reason that I reacted as I did to the comment that a single chirality indicates (sic!) a SINGLE path back in time. As you and others pointed out it might be one, it might be two or it might be both. Evopeach had some particulars about rna and replication instead. Gould in the end refused to write the word "form" without ambiguity to 0, 1 or 2 branching lineages. I think we have and can do (on evc) better than this.Edited by Brad McFall, : BBCodesEdited by Brad McFall, : spacing lost to software transfer

I concur, common descent does\is not need to be a necessary result -- it can be a matter of common resources.We see concentration of toxins in predators in similar manner than would apply to concentrations of raw materials for building cell materials -- it may come down to the ultimate prey - some herb or other - having preferred their sugar spun one way at the candy fair, and each organism consuming the salad of choice or in turn consuming the consumer, would also concentrate on the one sugar.There is too much we don't know about how much of which spin can be accomodated. We {as the sum of organisms} may also have lost any previous ability as supply was lost.So why do {plants\bacteria\algae} that ostensibly take raw materials from the environment direct rather than from some other organic source choose one side of the equations? Habit?

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Join the effort to unravel {AIDSHIV} with Team EvC! (click)

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we are limited in our ability to understand
by our ability to understand

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Then you might want to elaborate on the point you're trying to make. How about explaining your point as well as pointing out any of my text that you take issue with.
Are you saying that the exclusive use of one form of amino acid is not evidence of common descent? If you why not?

It absolutely matters in Darwin's case. The pathways required for replication, trancription, translation, and expression will not work using amino acids of opposite "handedness."
It could have began with both forms, but there is no evidence of this. Only the L forms are used.It doesn't make one iota of a difference what your "thought" is, if you have absolutely no evidence to support it.

He emailed me a few times after I joined a certain Yahoo group spouting off nonsense about how evolution violates the 2nd Law of Thermodynamics.

So, you reacted without any evidence to support your claim?
Central Dogma of Molecular Biology:
DNA RNA -> Protein
There is one path back in time. Unless, you can provide evidence of another. I won't hold my breath on that.

Again, it does not matter what you believe. D-amino acids are not interchangeable in biological sysytems. Do you have any evidence that they are? Any peer-reviewed articles?
Pick up a book on molecular biology. The "handedness" of biological molecules are vital for every fundamental process. The fact that all organisms use the L-form is evidence of common descent via DNA.

The evidence does not support this view. The common use of L-amino acids is due to the conservation of fundamental processes such as replication, transcription, translation, expression, and metabolism. It is due to the conservation of the genetic code. Besides the 3 stop codons, all of the rest code for L-amino acids. The use of D-amino acids would have required a different code, resulting in mirrored pathways, let alone left-handed B-DNA (which would presumably be needed for an L-amino proteome). The homology between genomes observed using tools of bioinformatics supports this view.

I did not say this and I do not mean that. There are 64 available codons in the genetic code. 3 of them are used as stop codons. We have 20 amino acids that they code for. All are of the L-form. That leaves 41 available codons that could have been used for D-forms, yet they are not. The remainder are used as redundant codons for the 20 L-amino acids.
You would would be hard pressed to find a statistical test that would indicate that this (0 in 41 samples) is not a significant difference.
Your argument has no validity. Until you can produce any evidence to the contrary, my statement is based on fact and is not based on belief and is accurate as written.
I find it interesting that non-specialists frequently feel that they have gained a special insight into a fundamental processes that educated, experienced professionals have somehow missed. This takes a special brand of arrogance.

I thought Peach's last post was more recent than that. My bad.
We've exchanged emails and he never reponds to specific points, always changing the subject.
Here is a brief list of his greatest claims off the top of my head:
1) The only energy the Earth receives from the Sun is in the form of heat.
He somehow has missed the change in the visible spectrum resulting in days and nights. Or, he does not attribute this energy to the Sun.
2) That the Earth is a closed system.
Yet, he concedes above that the Earth at least receives heat from the Sun which indicates by his admission that it is an open system.
3) That point mutations are 99.99% lethal.
Well, only 3 of the 64 codons are stop codons, and SNPs in the third position of the codon usually result in silent mutations (coding for the same amino acid) due to the degenerate nature of the genetic code. Also, many SNPs result in missense mutations that insert an amino acid with similar properties such as polar for polar. i.e.- a switch from serine (TCT) to threonine (ACT).
How he can get 99.99% is anyone's guess.

Should I restate my replies to you in language that is easier for you to understand? Would that make it easier for you to respond? You evidently do not, since you comment on things that you know absolutely nothing about.
Perhaps you should spend some time studying the fundamentals of molecular biology and biochemistry before running off at the mouth like this.

Sufficiency and necessity are not the same.

Brilliant. In other words, you have no idea of what you are talking about and you have no evidence to support what you say.
Thanks for playing.
By the way, the exclusive use of one form or the other is a necessity. They are not interchangeable. There would be some remnants of this in genomes if this were the case. There are not.