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Advances in Chirality and other problems of abiogenesis in the Origins of Life

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  • #31
    Originally posted by shunyadragon View Post
    The references document organics arriving and forming in large amounts during the asteroid impacts. Again your selective unethical dishonest citation of reverences to justify your agenda.
    So please give me a quote from the article showing that large amounts arrived and formed during asteroid impacts.

    Blessings,
    Lee
    "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

    Comment


    • #32
      Originally posted by lee_merrill View Post
      But pure homochirality is required if the first active biomolecule was a ribozyme.

      again and again and again it is not required in abiogenesis where the homochirality developed as the research cited described. Pure homochirality evolved first as described in the research cited, and then the complex life evolved in part based on homochirality

      So which attempt was a large chiral difference applicable to early earth?
      Incoherent. Attempt?!?!!? All the research cited so far described how homochirality evolved during abiogenesis.


      But this is another survey, I'm asking you to pick the best approach you have seen.
      First, IT IS NOT A SURVEY. No one was polled to determine the winner. The two articles cited describe the various research results of how homochirality evolved in the processes during abiogenesis, before the complex RNA/DNA life evolved. Neither you nor I can 'pick the best approach. I referred to what I considered the best reference, and asked you to respond and failed to respond. It is also possible that more than one of the natural processes for the evolution of homochirality was involved with the development of homochirality. They all represent peer reviewed research based on organic chemistry and the environments of the Hadean Eon that can lead to the evolution of homochirality.
      Glendower: I can call spirits from the vasty deep.
      Hotspur: Why, so can I, or so can any man;
      But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

      go with the flow the river knows . . .

      Frank

      I do not know, therefore everything is in pencil.

      Comment


      • #33
        Originally posted by shunyadragon View Post
        again and again and again it is not required in abiogenesis where the homochirality developed as the research cited described. Pure homochirality evolved first as described in the research cited, and then the complex life evolved in part based on homochirality
        Pure homochirality is required in abiogenesis, as stated in the article:

        Source: Chemistry World

        With both stereoisomers present, RNA cannot be polymerised. According to Blackmond, some people say ‘no homochirality, no life’ and so far that seems to be true. The big sticking point is what is known as enantiomeric cross-inhibition,3 or what Gerald Joyce jokingly calls biology’s ‘original syn’.

        Joyce, also at Scripps, coined this term over 20 years ago to describe why only single-handed chemistry can build biological polymers like RNA, and why the opposite handed molecules block assembly. ‘It turns out if you have nothing but one hand, the chemical copying mechanism works very nicely,’ he says, but things go wrong when there are building blocks of both chirality. ‘They basically poison each other’s polymerisation.’

        3. G F Joyce et al, Proc. Natl Acad. Sci. USA, 1987, 84, 4398

        Source

        © Copyright Original Source



        Incoherent. Attempt?!?!!? All the research cited so far described how homochirality evolved during abiogenesis.
        Well, you may wish it did, but the research cited so far describes (unsuccessful) attempts to produce homochirality in early earth conditions.

        The two articles cited describe the various research results of how homochirality evolved in the processes during abiogenesis, before the complex RNA/DNA life evolved.
        So how did homochirality evolve? Let's have it on the table.

        Blessings,
        Lee
        "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

        Comment


        • #34
          Originally posted by lee_merrill View Post
          So please give me a quote from the article showing that large amounts arrived and formed during asteroid impacts.

          Blessings,
          Lee
          Your literate read it for yourself.
          Glendower: I can call spirits from the vasty deep.
          Hotspur: Why, so can I, or so can any man;
          But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

          go with the flow the river knows . . .

          Frank

          I do not know, therefore everything is in pencil.

          Comment


          • #35
            Originally posted by lee_merrill View Post
            Pure homochirality is required in abiogenesis, as stated in the article:

            Source: Chemistry World

            With both stereoisomers present, RNA cannot be polymerised. According to Blackmond, some people say ‘no homochirality, no life’ and so far that seems to be true. The big sticking point is what is known as enantiomeric cross-inhibition,3 or what Gerald Joyce jokingly calls biology’s ‘original syn’.

            Joyce, also at Scripps, coined this term over 20 years ago to describe why only single-handed chemistry can build biological polymers like RNA, and why the opposite handed molecules block assembly. ‘It turns out if you have nothing but one hand, the chemical copying mechanism works very nicely,’ he says, but things go wrong when there are building blocks of both chirality. ‘They basically poison each other’s polymerisation.’

            3. G F Joyce et al, Proc. Natl Acad. Sci. USA, 1987, 84, 4398

            Source

            © Copyright Original Source

            False default in your English and selective citation as unusual. All this refers to is the processes in RNA/DNA life and not the processes in abiogenesis before RNA/DNA life existed. Primitive pre-life forms did not have RNA. RNA did not exist until homochirality formed.


            Well, you may wish it did, but the research cited so far describes (unsuccessful) attempts to produce homochirality in early earth conditions.
            False please cite specifically where this research states that it is unsuccessful. Please be specific.



            So how did homochirality evolve? Let's have it on the table.

            Blessings,
            Lee
            Two articles presented one by you that describe different ways the chemical evolution of homechirality can take place.
            Last edited by shunyadragon; 06-18-2020, 06:47 PM.
            Glendower: I can call spirits from the vasty deep.
            Hotspur: Why, so can I, or so can any man;
            But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

            go with the flow the river knows . . .

            Frank

            I do not know, therefore everything is in pencil.

            Comment


            • #36
              Originally posted by shunyadragon View Post
              All this refers to is the processes in RNA/DNA life and not the processes in abiogenesis before RNA/DNA life existed. Primitive pre-life forms did not have RNA. RNA did not exist until homochirality formed.
              Yet "no homochirality, no life" is a heading in the article, not "no homochirality, no RNA/DNA life."

              False please cite specifically where this research states that it is unsuccessful. Please be specific.
              Only one approach generated pure homochirality, and that approach wasn't applicable to early earth, as I recall. The article is behind a paywall now, and I can't copy from it.

              Two articles presented one by you that describe different ways the chemical evolution of homechirality can take place.
              No, two articles describing approaches that produced varying levels of chiral difference. Homochirality is still elusive.

              Blessings,
              Lee
              "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

              Comment


              • #37
                Originally posted by lee_merrill View Post
                Yet "no homochirality, no life" is a heading in the article, not "no homochirality, no RNA/DNA life."
                Miss quoting again as usual, "some people say ‘no homochirality, no life’ and so far that seems to be true. The big sticking point is what is known as enantiomeric cross-inhibition," which is only one of the sources you selectively cite in the article. The article covers many different research articles on the chemical evolution of homochirality, and you chose to selectively misquote one, which does not agree with the others.

                Note 'some people say,' which is not the conclusion of the other references. Again, and again did not apply to the formation of homochirality before RNA/DNA life existed as the other research described. If homochirality chemically evolved first you would then have RNA/DNA life.


                Only one approach generated pure homochirality, and that approach wasn't applicable to early earth, as I recall. The article is behind a paywall now, and I can't copy from it.

                No, two articles describing approaches that produced varying levels of chiral difference. Homochirality is still elusive.
                cshperspectives.cshlp.org/content/11/3/a032540.abstract is NOT behind a pay wall. It is free. Maybe your's is?

                More shell game of vague 'arguing from ignorance.'Nothing specifically cited to support your case.

                Still waiting . . .

                'As I recall' . . . is not citing the articles specifically which you failed to do, Not true, and does not reflect the articles you selectively cited. I

                Again several possibility from your source:Source:

                Source: https://www.chemistryworld.com/features/the-origin-of-homochirality/9073.article




                A theoretical model for symmetry breaking was proposed in the 1950s by British physicist Charles Frank, who suggested that in autocatalytic reactions, where the products are catalysts for their own formation, any small random asymmetry in the products will be amplified and will provide a way of enhancing one hand over another. A reaction confirming this idea was only found in 1995 by Japanese chemist Kenso Soai.4 His autocatalytic alkylation of pyrimidyl aldehydes with dialkylzincs is catalysed by its chiral alcohol product. Given a very small excess of the product in one chirality, the eventual yield of the reaction will have much more of that form than its mirror image – as high as 91% excess. ‘It gave experimental proof of concept,’ Blackmond says, but points out the one big flaw: ‘The actual chemistry isn’t at all prebiotically relevant.
                . . .
                Blackmond contends that it’s not enough to find a method that creates a single chiral product from achiral starting materials – the reaction has got to provide a way of doing this with the sorts of molecules that might have been present in the prebiotic world. In 2011, she found a way to take Sutherland’s route to RNA but make molecules of a single chirality. Her route to making RNA precursor molecules from racemic glyceraldehyde and 2-amino*oxazole still requires a chiral amino acid.7 Her ‘kinetic resolution’ method works by creating a reaction where one form of a molecule can react faster than the other. ‘You need something chiral to interact with them differently and we developed that,’ Blackmond says.

                Her reaction worked best with the left-handed l-amino acid proline. Using just 1% excess of the l form, it was possible to produce a product of 100% chiral purity. The process works because the l-amino acid reacts at different rates with the two stereo*isomers of glyceraldehyde. The l-sugar reacts more quickly with the l-amino acid and, on reacting with the oxazole, produces a homochiral three-component product. A similar preference was seen with the right-handed d-amino acid and d-sugar.

                ‘It’s an amazing reaction,’ says Blackmond. ‘It turns out that the natural hand of the amino acid sequesters the unnatural hand of the sugar, and vice versa, and that’s how the amplification occurs. So the sugar can be used to amplify the amino acid enantiomeric excess, or the amino acid can be used to amplify the sugars. Truly chicken or egg … or egg or chicken!’ Blackmond suggests that the enriched amino acid could have formed initially via a crystallisation process. ‘It could have been all of these things contributing a little bit over a long time.’

                © Copyright Original Source

                Last edited by shunyadragon; 06-19-2020, 08:45 PM.
                Glendower: I can call spirits from the vasty deep.
                Hotspur: Why, so can I, or so can any man;
                But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                go with the flow the river knows . . .

                Frank

                I do not know, therefore everything is in pencil.

                Comment


                • #38
                  Originally posted by shunyadragon View Post
                  Miss quoting again as usual, "some people say ‘no homochirality, no life’ and so far that seems to be true.
                  But I meant the section heading, not the text of the article. But "so far that seems to be true" also shows that homochirality is required.

                  Again several possibility from your source:Source:

                  Source: https://www.chemistryworld.com/features/the-origin-of-homochirality/9073.article


                  ‘It gave experimental proof of concept,’ Blackmond says, but points out the one big flaw: ‘The actual chemistry isn’t at all prebiotically relevant.
                  . . .
                  Her route to making RNA precursor molecules from racemic glyceraldehyde and 2-amino*oxazole still requires a chiral amino acid.

                  © Copyright Original Source

                  So it seems we're not there yet.

                  Blessings,
                  Lee
                  "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                  Comment


                  • #39
                    Originally posted by lee_merrill View Post
                    But I meant the section heading, not the text of the article. But "so far that seems to be true" also shows that homochirality is required.
                    This is what I call selective citing to justify your agenda, and not considering the article as a whole, and the other research articles. The different articles give different perspectives and results concerning the evolution of chemical chirality.


                    So it seems we're not there yet.
                    Not a satisfactory response. Nothing in the research cited considered their work 'unsuccessful.' and the reached different conclusions. In fact one successful method achieved 100% homochirality.

                    Arguing from ignorance' does not go far, because science has usually advanced to address the unknowns claim by the ID apologists. Since scientists never approach the goals of science in absolute terms of achievement. Science could always be 'not there yet.'
                    Last edited by shunyadragon; 06-20-2020, 05:37 PM.
                    Glendower: I can call spirits from the vasty deep.
                    Hotspur: Why, so can I, or so can any man;
                    But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                    go with the flow the river knows . . .

                    Frank

                    I do not know, therefore everything is in pencil.

                    Comment


                    • #40
                      Originally posted by lee_merrill View Post
                      So please give me a quote from the article showing that large amounts arrived and formed during asteroid impacts. I has also been documented that asteroids and meteors have brought organics to the earth.

                      Blessings,
                      Lee
                      The article indeed documents the organics produced by the impacts, and this section describes the literal huge amount of asteroid involved over the vast time the span of the Asteroid impact period of the Hadean Eon.

                      Source: https://www.nature.com/articles/s41598-020-66112-8



                      The amounts of extraterrestrial objects accreted during the LHB period has been estimated as 4 × 1023 g52, and the contents of metallic Fe in OCs (e.g., H chondrites) are ~10 wt%42. Therefore, a large amount of metallic Fe was provided by impacts. In the present study, reduction of Fe, followed by the formation of reduced species, initiated the formation of amino acids. The conversion of the consumed Fe to amino acid was 2 × 10−5 wt% and N2 to amino acid was 1 × 10−4 atm% in the present NH3-free OC analogue experiment. The amount of amino acid production by the Hadean impacts would not be small, considering the huge Fe flux during the late Hadean (~4 × 1022 g, assuming 10 wt% of total LHB amount) and almost infinite amounts of CO2 and N2 (e.g., 1021 g on the modern Earth or might have been half of the modern level) in atmosphere of the Earth at that time3,27,53. It is difficult to precisely estimate the amounts of amino acid products generated via natural impacts with the present experiments due to technical difficulties in the demonstration of large impacts, which are expected to yield more amino acids. Alternatively, the present yield would be a baseline amount along with variation.

                      Extraterrestrial delivery is another source of the building blocks of life on prebiotic Earth54,55,56. Many amino acids have been detected from meteorites57,58. However, the amounts of the delivery remained unclear, because the composition of the building blocks of life in different carriers, particularly micrometeorites that are regarded as the largest carrier, remained unclear52,59,60. Further investigations regarding both endogenous formation and exogenous delivery are indispensable for understanding the availability of the building blocks of life on prebiotic Earth.

                      Since impact events occur locally, produced organic compounds distribute locally around the site of the impacts. This may have advantage in subsequent chemical evolution, since enrichment is one of the most significant problem in chemical evolution of polymerization38,43,61.

                      Impact-induced amino-acid formation might have been possible on Noachian Mars. The high intensity of crater distribution on Martian Noachian highland surface suggests the presence of intense impacts on Mars before 3.7 billion years ago62,63. A considerable amount of geological and geophysical evidence indicates a wide distribution of liquid water on Noachian Mars63,64 (see Supplementary Information). Atmospheric modeling combined with geological data has suggested that the major atmospheric components of Noachian Mars were CO2 and N2 with minor amounts of reduced species (see Supplementary Information). Therefore, the results of the present study further suggest that Noachian impact events synthesized abiotic organic matter including amino acids on Mars. Complex organic matter found by Mars Science Laboratory in ~3.5 Ga sediments support this implication65. Thus, chemical evolution might have been promoted and accomplished to the formation of monomers of catalytic biopolymers even on Noachian Mars.

                      © Copyright Original Source

                      Last edited by shunyadragon; 06-20-2020, 05:54 PM.
                      Glendower: I can call spirits from the vasty deep.
                      Hotspur: Why, so can I, or so can any man;
                      But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                      go with the flow the river knows . . .

                      Frank

                      I do not know, therefore everything is in pencil.

                      Comment


                      • #41
                        Originally posted by shunyadragon View Post
                        The article indeed documents the organics produced by the impacts, and this section describes the literal huge amount of asteroid involved over the vast time the span of the Asteroid impact period of the Hadean Eon.

                        Source: https://www.nature.com/articles/s41598-020-66112-8


                        The amount of amino acid production by the Hadean impacts would not be small, considering the huge Fe flux during the late Hadean … It is difficult to precisely estimate the amounts of amino acid products generated via natural impacts with the present experiments due to technical difficulties in the demonstration of large impacts, which are expected to yield more amino acids.

                        © Copyright Original Source

                        So where does it say huge? Huge iron flux, but "not small" amino acid production, though it's difficult to estimate precisely.

                        Blessings,
                        Lee
                        "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                        Comment


                        • #42
                          Originally posted by shunyadragon View Post
                          This is what I call selective citing to justify your agenda, and not considering the article as a whole, and the other research articles. The different articles give different perspectives and results concerning the evolution of chemical chirality.
                          But all this has no bearing on the clear statement "no homochirality, no life."

                          Not a satisfactory response. Nothing in the research cited considered their work 'unsuccessful.' and the reached different conclusions. In fact one successful method achieved 100% homochirality.
                          Starting with chiral amino acids! So this would not be attuned to early earth.

                          Blessings,
                          Lee
                          "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                          Comment


                          • #43
                            Originally posted by lee_merrill View Post
                            So where does it say huge? Huge iron flux, but "not small" amino acid production, though it's difficult to estimate precisely.

                            Blessings,
                            Lee
                            I cited the reference, but I do take into consideration your weakness in math to understand the numbers in the reference. 'Huge' is just a word, but it is very descriptive of amount of asteroids and the associated organics described in the article. The article is well documented based on the evidence which your evading, and no need for splitting 'frog hairs'over 'precise amounts.'
                            Glendower: I can call spirits from the vasty deep.
                            Hotspur: Why, so can I, or so can any man;
                            But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                            go with the flow the river knows . . .

                            Frank

                            I do not know, therefore everything is in pencil.

                            Comment


                            • #44
                              Originally posted by lee_merrill View Post
                              But all this has no bearing on the clear statement "no homochirality, no life."
                              First, it is taken out of context, and again you are dishonestly selectively citing one phrase, and ignoring the whole article, which I have previously cited. Remember the article also 'some say . . . ' in the article. The conclusion of the whole article is NOT "no homochirality, no life."


                              Starting with chiral amino acids! So this would not be attuned to early earth.

                              Blessings,
                              Lee
                              No basis for this conclusion based on the whole context of the articles cited. The articles specifically demonstrated on how homochirality can form by chemical evolution in abiogenesis.
                              Glendower: I can call spirits from the vasty deep.
                              Hotspur: Why, so can I, or so can any man;
                              But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

                              go with the flow the river knows . . .

                              Frank

                              I do not know, therefore everything is in pencil.

                              Comment


                              • #45
                                Well, we're just going back and forth, to no avail, so I'll let you have the last word.

                                Blessings,
                                Lee
                                "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                                Comment

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