DNAunion responds to me:
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But achieving homochirality isn't a problem:
/*DNAunion*/ Wrong. That article does not demonstrate how homochirality can originate...the "self-replicating" molecules themsevles start out chirally pure: they then select the correct enantiomeric forms.
First, it was a start to more research. Not the sole piece of information.
Second, you're ignoring an important point in the paper: Mutations get corrected:
They further discovered that if they added "mutant" peptide templates with a single incorrectly handed molecule, these would not make more mutant templates. They would instead correct the mistake and catalyze the formation of new molecules with the correct composition.
It seems you're simplifying.
Here's some more analysis of that paper:
Biochemistry: Single-handed cooperation
Synthetic polymers are simpler than biological systems and provide a model for understanding the origin of homochirality in biomolecules. One proposal stems from observations that polymers made from building blocks of random handedness will contain mixtures of right- and left-handed blocks so complex that no two polymers will have identical stereochemistry. All the polymers will be chiral, but if one exists, it is unlikely that its mirror image will too. For small polymers consisting of only a few building blocks, the number of possible combinations of right- and left-handed blocks is small, and the mirror images are easily formed. However, for a polymer comprising 20 building blocks there are almost a million possibilities, and an enormous number of blocks would be required to build all the possible mirror images. Biological molecules often have over 100 building blocks, pushing the limits of available materials and making it extremely unlikely that a molecule and its mirror image can be prepared in the same batch. If the sample of polymers contained some that were self-replicating, it is reasonable that the most efficient one will emerge, and only this homochiral polymer will exist.
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Also, the calculation I was referencing dealt with polynucleotides, not peptides.
Is there some reason to assume that chirality in polynucleotides would not have similar methods of establishment compared to peptides?
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By the way, there are other problems with using that paper to support origin of life, as in, "See, this is how life arose".
Nobody is saying that. Is there a particular reason why you are assuming that the work into how life could have arisen necessarily means that what is found is the precise method about how it actually did? As the second link I just provided states, "The origin of one-handedness in biological molecules is not yet clear."
The point is that there are ways to achieve homochirality. We should not simply claim that because something is difficult for us right now means that it will never be possible to figure out. Too many times we have claimed something to be impossible (like the synthesis of organic compounds from inorganic reagents) only to find out that it is quite possible.
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For example, despite the misleading term used by the authors and others, the peptides do not self-replicate.
Incorrect. Did you read the article?
For the "template" peptides to replicate, the correctly-handed components in the mixture would have to stick to the correct location on the peptides and then link up, forming exact copies of the template molecules, and this is exactly what they observed.
What do you think "For the 'template' peptides to replicate" means?
Not only did the results show that the peptides favored the synthesis of correct duplicates, but the duplicates auto-catalyzed the reaction, speeding it up.
What do you think "the peptides favored the synthesis of correct duplicates" means?
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Rrhain
WWJD? JWRTFM!