Evolution: Research Discovers Chemical Reactions Describing Transition to Biotic Chemistry

Discussion in 'Biology & Genetics' started by Tiassa, Aug 2, 2022.

  1. Tiassa Let us not launch the boat ... Staff Member

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    37,137
    The short form, from NASA Astrobiology↱:

    Discovery alert: #astrobiologists have found a new set of chemical reactions that could explain how life began on the early Earth. The research also helps bring together two sides of a long-standing debate about the importance of carbon dioxide to early life.

    The press release from Scripps↱:

    "We've come up with a new paradigm to explain this shift from prebiotic to biotic chemistry," says Ramanarayanan Krishnamurthy, PhD, an associate professor of chemistry at Scripps Research, and lead author of the new paper, published July 28, 2022 in the journal Nature Chemistry. "We think the kind of reactions we've described are probably what could have happened on early earth" ....

    .... In cells today, amino acids are generated from precursors called α-keto acids using both nitrogen and specialized proteins called enzymes. Researchers have found evidence that α-keto acids likely existed early in Earth's history. However, many have hypothesized that before the advent of cellular life, amino acids must have been generated from completely different precursors, aldehydes, rather than α-keto acids, since enzymes to carry out the conversion did not yet exist. But that idea has led to debate about how and when the switch occurred from aldehydes to α-keto acids as the key ingredient for making amino acids ....

    .... "We were expecting it to be quite difficult to figure this out, and it turned out to be even simpler than we had imagined," says Krishnamurthy. "If you mix only the keto acid, cyanide and ammonia, it just sits there. As soon as you add carbon dioxide, even trace amounts, the reaction picks up speed."

    Because the new reaction is relatively similar to what occurs today inside cells—except for being driven by cyanide instead of a protein—it seems more likely to be the source of early life, rather than drastically different reactions, the researchers say. The research also helps bring together two sides of a long-standing debate about the importance of carbon dioxide to early life, concluding that carbon dioxide was key, but only in combination with other molecules.

    In the process of studying their chemical soup, Krishnamurthy's group discovered that a byproduct of the same reaction is orotate, a precursor to nucleotides that make up DNA and RNA. This suggests that the same primordial soup, under the right conditions, could have given rise to a large number of the molecules that are required for the key elements of life.

    There are probably a few ways to look at this, but something that stands out to me has to do with Creationism and related pseudoscience: The thing about theology is that it's not really going to change much unless God happens to show up; compared to questions of evolution, the Creationist argument is somewhat closed, and cannot develop into something significantly different without vastly revising what is supposed to be immutable. It was easy enough to say, of science, that all the audience really needed to do was stay tuned.

    Even still, the present moment feels kind of strange; Twitter hype is what it is, but reading through the Scripps release it gets harder to shake the sense that, yes, this one looks like it might be big.

    It's one thing if I want to chuckle at the thought of God investing hyperuniform disorder in chickens, or marvel at suggestions of Lamarckian adaptation in mammals, and so on, but chemical reactions describing a transition into biotic chemistry make for something of a bellringer.

    And the thing is, the politics really are nearly the last thing we ought to be worrying about, even if it is kind of a strange time in society. I just hear the word, "Science!" like from the Dolby song↱, echo and resound. It's hard to imagine how many pathways for scientific inquiry this paper opens, but it feels like something big.
    ____________________

    Notes:

    @NASAAstrobiology. "Discovery alert: #astrobiologists have found a new set of chemical reactions that could explain how life began on the early Earth. The research also helps bring together two sides of a long-standing debate about the importance of carbon dioxide to early life." Twitter. 1 August 2022. Twitter.com. 1 August 2022. https://bit.ly/3cZUL2z

    Scripps Research. "Scripps Research scientists discover new 'origins of life' chemical reactions". Press Release. 28 July 2022. Scripps.edu. 1 August 2022. https://bit.ly/3BtnyXw

    See Also:

    Pulletikurt, Sunil, Mahipal Yadav, Greg Springsteen, and Ramanarayanan Krishnamurthy. "Prebiotic synthesis of α-amino acids and orotate from α-ketoacids potentiates transition to extant metabolic pathways". Nature Chemistry. 28 July 2022. https://go.nature.com/3JoJxkj
     
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  3. Write4U Valued Senior Member

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    This has been the theme of Robert Hazen from the Carnegie Institute. He is a mineralogist and has long proposed that life originated from chemical reactions given a dynamic environment, some fundamental minerals, large surfaces and lots of time.
    An earthlike planet can perform an incredible numbers of naturally occurring chemical reactions. He estimates that the earth has performed some 2 trillion, quadrillion, quadrillion, quadrillion chemical experiments in its 4 billion-year existence.

    He demonstrates that with the presence of water, carbon and clay surfaces in a dynamic (violent) environment, eventually the chemical interactions will yield self-replicating polymers of biochemical molecules as well as the self-organization of cellular structures in water.

    Interestingly, it seems that the universe is not tuned for life, but life is tuned to universal conditions. This is why life ranges from extremophiles that must have extreme environments to survive to, tardigrades that can tolerate all environments, including space, to the May Fly that has a winged life for just 24 hrs and must procreate within that time.

    Hazen's theory rests on the premise that life is neither inevitable nor extremely rare, but in certain environments is probabilistic and given sufficient space and time will self-organize into life resembling organisms.

    The following is really a very nice introductory lecture, where he lays out the fundamental premise of naturally self-organizing complex biochemical patterns;
    (start at 12:00 to avoid a lengthy introduction)

    Hazen has several more formal presentations on YouTube that have more in-depth scientific content.
     
    Last edited: Sep 14, 2022
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  5. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Any hint about scientists making a soup containing these chemicals and letting them do their thing?

    I'm reminded of the joke about the atheists scientists who went to heaven

    Sitting on the edge of a cloud during her obligatory audience with god she remarked

    "You are not do special anymore. Us scientists can do what you can do. Even create life"


    "I would like to see that"

    Scientists begins to reach down to Earth

    "What are you doing?"

    "Picking up some ingredients to make a primordial soup"

    "Err no. You have to make your own ingredients"

    Please Register or Log in to view the hidden image!

     
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