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On 17/06/2025 2:17 am, RonO wrote:It does not imply any pure source. Life and the initial self replicators would have depended on catalyitic activity in their environment or that could be found in the conglomerate of molecules that they were made of. It turns out that only one form (L or D) fit into reactive sites of a lot of enzymes in a way that the reaction can occur. D and L forms have different shapes, and this often means that the reactive portion is not in the right position for the enzymatic reaction to occur for one or the other. In the case that I was wrong about it turned out that both D and L amino acids could be polymerized by the ribozyme peptidase, and it was the ribosome and how it bound the acylated tRNA that made it so the D form was not held in the correct position for the reaction to occur.On 6/15/2025 9:06 PM, MarkE wrote:I've asked LD this same question. I'd be interested in your comments in the my logic and understanding of the issue, as follows.On 16/06/2025 9:57 am, MarkE wrote:>On 15/06/2025 7:45 am, RonO wrote:>https://evolutionnews.org/2025/06/jonathan-wells-cleared-the- ground- for- intelligent-design/>
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>Denial seems to be all that the ID perps ever had, and the only thing that creationists like Tour and MarkE can continue with,>
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Hi Ron, speaking of denial, Tour and OoL, here's a real example of denial, in this case denial of the OoL chirality problem: https:// www.youtube.com/shorts/ArnQyn5tdT4
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"The origin of life, based on the homochirality of biomolecules, is a persistent mystery."
— Devínsky, F. (2021). https://www.mdpi.com/2073-8994/13/12/2277
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“Homochirality remains one of the central unsolved problems in origin- of-life research.”
— Lahav, N. (1999). Biogenesis: Theories of Life's Origin
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I think that these guys just do not understand that lifeforms need enzymes to exist, and it was the first enzymes that set the chirality of the molecules used. Why doesn't life use all D forms of every molecule? why use L forms of amino acids and D forms for sugars? Anyone can look to see that the existing enzymes use the L form of amino acids, so what is the mystery? All the enzymes that use or produce amino acids would be selected to use L forms. The exception are the enzymes that convert D forms to L forms. The two chiral forms will spontaneously change in solution, so life has evolved enzymes that make the D forms into L forms that can be used by the existing enzymes.
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This denial will never support your Biblical beliefs. Nothing about chirality is in the Bible, only things that make the chirality issue something that does not support Biblical creationism. It doesn't matter if some god set the chirality because it was not the god described by the Bible.
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Ron Okimoto
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Life's molecules are now strictly homochiral (e.g. proteins composed of only L-amino acids), therefore either they developed this way from the beginning, or were purified by a later process.
If the former, this implies either an enantiomerically pure source of monomers, or a prebiotic polymerisation process that selected only one form. You suggest "specific catalysts [which] produce chirally specific reactions", but what reactions exactly, in what prebiotically plausible situation, and with what necessary amounts of material and time?
If the latter, this would involve the complete substitution of L for R units and/or removal of R units. But this would change the structure of say a protein and erase its evolved function. This alone rules out this option.As I noted L amino acids are used in the synthesis of nucleotides. Life has evolved mechanisms to change D forms of some of these nucleotide making amino acids from D to L so that the biosynthetic enzymes can use them. In solution L and D forms can convert to one or the other at a low rate, and they can be made in some reactions, so you have to deal with D amino acids. Some bacteria even use D amino acids for a sort of defense mechanism. In some cases that I recall only L amino acids work in the reaction, but in others you need to use L amino acids to make the product whose structure can be used for the next step, and is likely why some D amino acids are changed to L. It is likely important to change from D to L because some of the pathways for getting this done are at least two steps where you have to break down the amino acid and then put it back together into the L form.
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