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

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  • #16
    Originally posted by shunyadragon View Post
    Homchirality is an attribute of complex life...
    It's an attribute of all life: "Life exists in single-handed forms."

    In fact the proposals in the article describe 'how homochirality developed over time.
    They describe various approaches, but all seem inconclusive: "the problem may seem trivial at first glance, but chemists still do not understand how it happened."


    The pros and cons of how and when homochirality developed is most definitely at issue here.
    That's fine, but the reason I brought up the article is that you said there is no evidence that 100% homochirality is required. There is evidence, there are clear statements in the article that it is required. One section is even titled "No homochirality, no life".

    Selective citations do not justify your religious agenda. The proposals for the development of homochirality developed in the pre-life evolution that led to homochirality.
    So what is the best approach describing how homochirality developed?

    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


    • #17
      And you have yet to tell me whether the building blocks in the second article you posted were racemic.

      Originally posted by lee_merrill View Post
      Source: Reasons to Believe

      These requirements demand that the origin of homochiral amino acids and ribose sugars must precede the origin of proteins, DNA, and RNA. That is, without preexisting large reservoirs of exclusively left-handed amino acids for each of the 19 bioactive amino acids and preexisting large reservoirs of exclusively right-handed ribose sugars, any naturalistic assembly of proteins, DNA, and RNA is ruled out. Without such reservoirs, naturalistic origin-of-life models are prohibited.

      Source

      © Copyright Original Source

      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


      • #18
        Originally posted by lee_merrill View Post
        It's an attribute of all life: "Life exists in single-handed forms."
        True, so what?!?!?! I believe The Lurch and I have addressed this many times. The formation of homochirality took place in the processes of abiogenesis as the the article and the Lurch previously described


        They describe various approaches, but all seem inconclusive: "the problem may seem trivial at first glance, but chemists still do not understand how it happened."
        'Seem' is a problem and does not reflect what the article described. ]Arguing; from ignorance is your greatest strength. All the ways chirality formed in the processes of abiogenesis in the formation of the first RNA/DNA life. The only thing inconclusive is which of the chemically' possible' ways of homochirility formed in the processes that resulted in the first RNA.

        None of the references that described the possible chemical processes proposed that you need perfect homochirility for the process to become a part of the formation of the first RNA. They all describe homochirality forming over time by chemical processes described in the research.



        That's fine, but the reason I brought up the article is that you said there is no evidence that 100% homochirality is required. There is evidence, there are clear statements in the article that it is required. One section is even titled "No homochirality, no life".
        That is not what the article described if you read the whole article. Of course in complex life forms with RNA/DNA require homochirality, but you are neglecting the 'facts' that the article describes how homochirality can form in several different ways in pre-life abiogenesis.


        So what is the best approach describing how homochirality developed?
        There is no best way homochirality formed at present. The research references provided chemically valid ways homochirality can form by inorganic chemistry in the abiogenesis pre=life prior to the formation RNA/DNA life.

        You are most definitely misrepresenting the article as a whole. and selectively cite only what justifies your agenda.
        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


        • #19
          Originally posted by lee_merrill View Post
          And you have yet to tell me whether the building blocks in the second article you posted were racemic.



          Blessings,
          Lee
          I already determined that your source is not a reliable scientific source and has a religious agenda not accepted by the sciences of evolution and abiogenesis. Simple response is in inorganic nature most organic chemical are originally mostly racemic like those that arrived on asteroids in huge amounts during the Hadean Eon of earth's history. . There is evidence as cited that organics from asteroids are not totally racemic. The processes of abiogenesis evolve homochirality selectively as likely by one of the methods in the source you cited as preferencal survival advantage for the complex life forms to evolve. Those that did not have homochirality did not survive.

          There is some indication that the early primitive forms of prokaryotes like archaea and bacteria had homochirality and imparted homochirality on the other first primitive life forms as the origin of the nucleus and the other organelles of cells that the early bacteria invaded.

          I only respond to scientific articles like you cited and dishonestly misrepresented.
          Last edited by shunyadragon; 06-13-2020, 10:53 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


          • #20
            This article goes into some detail concerning the experimental studies concerning how chirality formed during abiogenesis.

            Source: cshperspectives.cshlp.org/content/11/3/a032540.abstract



            The Origin of Biological Homochirality
            Donna G. Blackmond
            +Author Affiliations

            Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037
            Correspondence: blackmond@scripps.edu
            SUMMARY
            The fact that sugars, amino acids, and the biological polymers they construct exist exclusively in one of two possible mirror-image forms has fascinated scientists and laymen alike for more than a century. Yet, it was only in the late 20th century that experimental studies began to probe how biological homochirality, a signature of life, arose from a prebiotic world that presumably contained equal amounts of both mirror-image forms of these molecules. This review discusses experimental studies aimed at understanding how chemical reactions, physical processes, or a combination of both may provide prebiotically relevant mechanisms for the enrichment of one form of a chiral molecule over the other to allow for the emergence of biological homochirality.

            6 CONCLUDING REMARKS
            The implications of the single chirality of biological molecules may be viewed in the context of increasing complexity at both the molecular and macroscopic levels. In the molecular sciences research, this has been codified as the field of“systems chemistry”(von Kiedrowski, 2005), which seeks to understand the chemical roots of biological organization by studying the emergence of system properties that may be different from those showed individually by the components in isolation. The abiotic construction of homochiral genetic polymers from molecular building blocks implies at least some minimal degree of enantioenrichment at the molecular level, if not molecular homochirality, to ensure efficiency as RNA or peptide chains grow in length. This review has described a variety of work invoking either chemical or physical processes, or both, that might allow the emergence of biological homochirality

            © Copyright Original Source

            Last edited by shunyadragon; 06-14-2020, 06:58 AM.
            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


            • #21
              Originally posted by shunyadragon View Post
              True, so what?!?!?! I believe The Lurch and I have addressed this many times. The formation of homochirality took place in the processes of abiogenesis as the the article and the Lurch previously described.
              Where has TheLurch described this? And in fact, the article only surveys attempts that have been unsuccessful at providing a way homochirality could have come about: "the problem may seem trivial at first glance, but chemists still do not understand how it happened."

              None of the references that described the possible chemical processes proposed that you need perfect homochirility for the process to become a part of the formation of the first RNA.
              The reference above states very explicitly that perfect homochirality is required. One section is even titled "No homochirality, no life".

              There is no best way homochirality formed at present.
              You can't tell me the best way? I only ask you to tell me the best way for homochirality to form, and let's discuss this.

              Simple response is in inorganic nature most organic chemical are originally mostly racemic like those that arrived on asteroids in huge amounts during the Hadean Eon of earth's history.
              Alright then, so they need to address the chirality problem. But how is it that organic chemicals arrived in huge amounts? I need a reference...

              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


              • #22
                Originally posted by shunyadragon View Post
                This article goes into some detail concerning the experimental studies concerning how chirality formed during abiogenesis.

                Source: cshperspectives.cshlp.org/content/11/3/a032540.abstract



                This review discusses experimental studies aimed at understanding how chemical reactions, physical processes, or a combination of both may provide prebiotically relevant mechanisms for the enrichment of one form of a chiral molecule over the other to allow for the emergence of biological homochirality.… This review has described a variety of work invoking either chemical or physical processes, or both, that might allow the emergence of biological homochirality

                © Copyright Original Source

                "May" and "might" are evidence of tenativeness, not so conclusive as showing "how chirality formed".

                Blessings,
                Lee

                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


                • #23
                  Originally posted by lee_merrill View Post
                  "May" and "might" are evidence of tenativeness, not so conclusive as showing "how chirality formed".

                  Blessings,
                  Lee

                  Blessings,
                  Lee
                  Misquoting out of context.
                  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


                  • #24
                    Originally posted by lee_merrill View Post
                    Where has The Lurch described this? And in fact, the article only surveys attempts that have been unsuccessful at providing a way homochirality could have come about: "the problem may seem trivial at first glance, but chemists still do not understand how it happened."
                    The Lurch repeatedly described that pure homochirality is not required in pre-life forms of abiogenesis, and the chemical processes of abiogenesis are what lead to the complex RNA/DNA life where homochirality evolved and the early pre-life forms do not require perfect homochirality.

                    No where in the articles I cited concluded that the research into the formation of homochirality during abiogenesis was unsuccessful.

                    Your habit of citing things out of context to justify your agenda is notorious and unethical.


                    The reference above states very explicitly that perfect homochirality is required. One section is even titled "No homochirality, no life".
                    Citation out of context of only one of the references in the article. IT ONLY REFERS TO COMPLEX RNA/DNA LIFE, and not the processes of abiogenesis that result in the evolution of RNA/DNA life.




                    [You can't tell me the best way? I only ask you to tell me the best way for homochirality to form, and let's discuss this.
                    I am not sure what you want to discuss. The articles only referred to 'successful' research that proposed different ways homochirality can take place in the natural processes of abiogenesis. As to which one is the best I will leave that up to future research, and neither of us are qualified to make that determination.


                    Alright then, so they need to address the chirality problem. But how is it that organic chemicals arrived in huge amounts? I need a reference...

                    Blessings,
                    Lee
                    You already have two references with numerous reference to the research that described the research concerning the evolution of homochirality during abiogenesis. These research articles reference and address the chirality problem.
                    Last edited by shunyadragon; 06-14-2020, 06:34 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


                    • #25
                      Originally posted by shunyadragon View Post
                      The Lurch repeatedly described that pure homochirality is not required in pre-life forms of abiogenesis, and the chemical processes of abiogenesis are what lead to the complex RNA/DNA life where homochirality evolved and the early pre-life forms do not require perfect homochirality.
                      Well, what about the RNA-world hypothesis, where the first biologically active molecule was a ribozyme?

                      No where in the articles I cited concluded that the research into the formation of homochirality during abiogenesis was unsuccessful.
                      Every one of the attempts was either a small chiral difference, or not applicable to early earth.

                      Originally posted by lee_merrill
                      The reference above states very explicitly that perfect homochirality is required. One section is even titled "No homochirality, no life".
                      Citation out of context of only one of the references in the article. IT ONLY REFERS TO COMPLEX RNA/DNA LIFE, and not the processes of abiogenesis that result in the evolution of RNA/DNA life.
                      The quote is not "no homochirality, no complex rna/dna life", though.

                      I am not sure what you want to discuss. The articles only referred to 'successful' research that proposed different ways homochirality can take place in the natural processes of abiogenesis. As to which one is the best I will leave that up to future research, and neither of us are qualified to make that determination.
                      So let's have you pick a good method, then, and discuss that.

                      You already have two references with numerous reference to the research that described the research concerning the evolution of homochirality during abiogenesis. These research articles reference and address the chirality problem.
                      But I was asking for references about your claim that organic chemicals arrived in huge amounts.

                      Blessings,
                      Lee
                      Last edited by lee_merrill; 06-14-2020, 07:57 PM.
                      "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


                      • #26
                        Originally posted by lee_merrill View Post
                        Well, what about the RNA-world hypothesis, where the first biologically active molecule was a ribozyme?
                        What about?!?!? I am not even addressing this in this topic.

                        Every one of the attempts was either a small chiral difference, or not applicable to early earth.
                        False.


                        The quote is not "no homochirality, no complex rna/dna life", though.
                        This is true, but you missed th epoint is "if homochirality does not evolve in abiogenesis there is no life.

                        Still selectively citing one liners to justify your agenda.

                        So let's have you pick a good method, then, and discuss that.
                        There are all good in one way or another, and there may be a combination. Pick this reference: https://cshperspectives.cshlp.org/co....full.pdf+html and go for it pick one, but it will be senseless. The problem is you have no qualifications in organic chemistry and abiogenesis to critique any one.


                        But I was asking for references about your claim that organic chemicals arrived in huge amounts.

                        Blessings,
                        Lee[/QUOTE]
                        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


                        • #27
                          Originally posted by lee_merrill View Post
                          But I was asking for references about your claim that organic chemicals arrived in huge amounts.
                          Following is a beginning, more to follow . . .

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



                          08 June 2020
                          Impact-induced amino acid formation on Hadean Earth and Noachian Mars
                          Yuto Takeuchi, Yoshihiro Furukawa, Takamichi Kobayashi, Toshimori Sekine, Naoki Terada & Takeshi Kakegawa
                          Scientific Reports volume 10, Article number: 9220 (2020) Cite this article

                          Abstract

                          Abiotic synthesis of biomolecules is an essential step for the chemical origin of life. Many attempts have succeeded in synthesizing biomolecules, including amino acids and nucleobases (e.g., via spark discharge, impact shock, and hydrothermal heating), from reduced compounds that may have been limited in their availabilities on Hadean Earth and Noachian Mars. On the other hand, formation of amino-acids and nucleobases from CO2 and N2 (i.e., the most abundant C and N sources on Earth during the Hadean) has been limited via spark discharge. Here, we demonstrate the synthesis of amino acids by laboratory impact-induced reactions among simple inorganic mixtures: Fe, Ni, Mg2SiO4, H2O, CO2, and N2, by coupling the reduction of CO2, N2, and H2O with the oxidation of metallic Fe and Ni. These chemical processes simulated the possible reactions at impacts of Fe-bearing meteorites/asteroids on oceans with a CO2 and N2 atmosphere. The results indicate that hypervelocity impact was a source of amino acids on the Earth during the Hadean and potentially on Mars during the Noachian. Amino acids formed during such events could more readily polymerize in the next step of the chemical evolution, as impact events locally form amino acids at the impact sites.

                          Introduction

                          The composition of early Earth’s atmosphere has been a subject of discussion. The atmosphere was once regarded as strongly reduced, composed mostly of CH4, NH3, and H21. Since approximately 40 years ago, a CO2-N2 dominated neutral atmosphere which was equilibrated to oxidized silicate mantle/crust, has been favored2,3,4,5. More recently, addition of reduced species to the atmosphere by the late veneer and the late heavy bombardment (LHB) have been proposed6,7,8,9,10,11. Although such local events might have provided reduced volatiles, the quantity of reduced species provided to the atmosphere remained unclear.

                          Initiated by Miller’s 1953 experiment, the formation of amino acids and nucleobases by spark discharge from reduced reactants (e.g., CO, CH4, and H2) has long been investigated as a potential source of the building blocks of life12,13. The yields of amino acids and other organic compounds are significantly sensitive to the amounts of reduced compounds13. The formation of amino acids from non-reduced species (i.e., CO2, N2, and H2O) by spark discharge has been proposed14,15. The formation reported in Plankensteiner et al.14 is coupled by the oxidation of Cu electrode, which is not available in natural spark discharge in the atmosphere. Spark-discharge with carbonate buffer reported by Cleaves et al.15 might have worked as a source of prebiotic amino acid, although ascorbate hydrolysis used in the work was challenged by a subsequent spark discharge study as a source of amino acid contamination16. Therefore, an experimentally-supported geological event that synthesizes amino acids is limited in spark discharge on neutral ocean. For other methods, such as shock-heating of the atmosphere, photochemical reactions, and proton irradiation, studies have reported that the formation of amino acids were limited to experiments using reduced C and N sources12,13,17,18,19,20,21,22. Formation of nucleobases is more significantly limited to experiments using reduced C and N sources21,23,24,25. They have not, however, been established using CO2 and N2, which were major terrestrial sources of C and N during the Hadean. A previous work reported amino acid formation by laser irradiation to CO2-N2-H2O without reductants26. However, it is not clear whether the detected amino acids were products or contaminants.

                          Several studies propose a high CO2 partial pressure for the early Hadean2,3,27. This suggestion leads to the possibility that concentrations of dissolved inorganic carbon, e.g., HCO3−, in the Hadean oceans were most likely much higher than of those in today’s oceans. Several sources of NH3 during the Hadean have been proposed. Most of these previous studies investigated the reduction of nitrogen oxides by Fe-sulfides, metallic Fe, or Fe2+ in rocks or ocean28,29,30,31. Even considering these sources, models suggest that there were significantly low NH3 concentrations in the oceans (e.g., 10−5 mol/L)32. Formation of organic compounds around hydrothermal vents is a popular model for an endogenous organic source. However, the formation of amino acids has only been demonstrated in experiments using fluid analogues containing reduced C and reduced N compounds (e.g., formaldehyde, NH3, and HCN) in extremely high concentrations19,33. Amino-acid synthesis has not been shown using non-reduced compounds, which were common in hydrothermal fluids34. Furthermore, the chemical equilibrium at high temperatures that are characteristic of hydrothermal vents has been found to favor amino-acid degradation rather than synthesis34.

                          © Copyright Original Source

                          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


                          • #28
                            Originally posted by shunyadragon View Post
                            Following is a beginning, more to follow . . .

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



                            08 June 2020
                            Impact-induced amino acid formation on Hadean Earth and Noachian Mars
                            Yuto Takeuchi, Yoshihiro Furukawa, Takamichi Kobayashi, Toshimori Sekine, Naoki Terada & Takeshi Kakegawa
                            Scientific Reports volume 10, Article number: 9220 (2020) Cite this article

                            Although such local events might have provided reduced volatiles, the quantity of reduced species provided to the atmosphere remained unclear.

                            © Copyright Original Source

                            So this would not support huge amounts of organic chemicals arriving on 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


                            • #29
                              Originally posted by lee_merrill View Post
                              So this would not support huge amounts of organic chemicals arriving on early earth...

                              Blessings,
                              Lee
                              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.
                              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


                              • #30
                                Originally posted by shunyadragon View Post
                                Originally posted by shunyadragon
                                The Lurch repeatedly described that pure homochirality is not required in pre-life forms of abiogenesis, and the chemical processes of abiogenesis are what lead to the complex RNA/DNA life where homochirality evolved and the early pre-life forms do not require perfect homochirality.
                                Originally posted by lee_merrill
                                Well, what about the RNA-world hypothesis, where the first biologically active molecule was a ribozyme?
                                What about?!?!? I am not even addressing this in this topic.
                                But pure homochirality is required if the first active biomolecule was a ribozyme.

                                Originally posted by lee_merrill
                                Every one of the attempts was either a small chiral difference, or not applicable to early earth.
                                False.
                                So which attempt was a large chiral difference applicable to early earth?

                                There are all good in one way or another, and there may be a combination. Pick this reference: https://cshperspectives.cshlp.org/co....full.pdf+html and go for it pick one, but it will be senseless. The problem is you have no qualifications in organic chemistry and abiogenesis to critique any one.
                                But this is another survey, I'm asking you to pick the best approach you have seen.

                                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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