Chemical evolution:

Discussion in 'Biology & Genetics' started by paddoboy, Aug 7, 2020.

  1. paddoboy Valued Senior Member

    Messages:
    27,534
    https://phys.org/news/2020-08-life-chemical-evolution-tiny-gulf.html

    Origins of life: Chemical evolution in a tiny Gulf Stream:

    Please Register or Log in to view the hidden image!


    Hot fluids meet a cold sea: Local temperature gradients in porous volcanic rock on the early Earth could have facilitated the self-replication of RNA strands. Credit: Picture Alliance

    Chemical reactions driven by the geological conditions on the early Earth might have led to the prebiotic evolution of self-replicating molecules. Scientists at Ludwig-Maximilians Universitaet (LMU) in Munich now report on a hydrothermal mechanism that could have promoted the process.

    Life is a product of evolution by natural selection. That's the take-home lesson from Charles Darwin's book "The Origin of Species," published over 150 years ago. But how did the history of life on our planet begin? What kind of process could have led to the formation of the earliest forms of the biomolecules we now know, which subsequently gave rise to the first cell? Scientists believe that, on the (relatively) young Earth, environments must have existed, which were conducive to prebiotic, molecular evolution. A dedicated group of researchers is engaged in attempts to define the conditions under which the first tentative steps in the evolution of complex polymeric molecules from simple chemical precursors could have been feasible. "To get the whole process started, prebiotic chemistry must be embedded in a setting in which an appropriate combination of physical parameters causes a non-equilibrium state to prevail," explains LMU biophysicist Dieter Braun. Together with colleagues based at the Salk Institute in San Diego, he and his team have now taken a big step toward the definition of such a state. Their latest experiments have shown the circulation of warm water (provided by a microscopic version of the Gulf Stream) through pores in volcanic rock can stimulate the replication of RNA strands. The new findings appear in the journal Physical Review Letters.

    As the carriers of hereditary information in all known lifeforms, RNA and DNA are at the heart of research into the origins of life. Both are linear molecules made up of four types of subunits called bases, and both can be replicated—and therefore transmitted. The sequence of bases encodes the genetic information. However, the chemical properties of RNA strands differ subtly from those of DNA. While DNA strands pair to form the famous double helix, RNA molecules can fold into three-dimensional structures that are much more varied and functionally versatile. Indeed, specifically folded RNA molecules have been shown to catalyze chemical reactions both in the test-tube and in cells, just as proteins do. These RNAs therefore act like enzymes, and are referred to as 'ribozymes." The ability to replicate and accelerate chemical transformations motivated the formulation of the "RNA world' hypothesis. This idea postulates that, during early molecular evolution, RNA molecules served both as stores of information like DNA, and as chemical catalysts. The latter role is performed by proteins in today's organisms, where RNAs are synthesized by enzymes called RNA polymerases.
    more at link.......................

    the paper:
    https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.048104

    ABSTRACT:
    The RNA world scenario posits replication by RNA polymerases. On early Earth, a geophysical setting is required to separate hybridized strands after their replication and to localize them against diffusion. We present a pointed heat source that drives exponential, RNA-catalyzed amplification of short RNA with high efficiency in a confined chamber. While shorter strands were periodically melted by laminar convection, the temperature gradient caused aggregated polymerase molecules to accumulate, protecting them from degradation in hot regions of the chamber. These findings demonstrate a size-selective pathway for autonomous RNA-based replication in natural nonequilibrium conditions.


     
    Write4U and Yazata like this.
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. pluto2 Valued Senior Member

    Messages:
    1,048
    I'm starting to lose faith in science because scientists still have no clue how the human body works and why the body works differently in different people.

    Scientists don't even know why we people feel and process pain very differently than others.

    The problem with science is that some influential scientists are too arrogant to admit that there is a problem.

    Science has become too political and less focused on progress in obtaining objective knowledge and to seek means to reach the truth. Science obviously does not progress and this is why I am disappointed in this whole enterprise.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Beer w/Straw Transcendental Ignorance! Valued Senior Member

    Messages:
    5,857
    Conspiracy?

    It may be truth. You should investigate.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. exchemist Valued Senior Member

    Messages:
    10,147
    Thank you, Eeyore.

    Please Register or Log in to view the hidden image!

     
    sideshowbob likes this.
  8. sideshowbob Sorry, wrong number. Valued Senior Member

    Messages:
    6,205
    Science is devastated. it doesn't know how it will be able to go on without your support.
     
  9. billvon Valued Senior Member

    Messages:
    19,261
    We have learned an amazing amount. I am constantly in awe of what we know about the immune system, for example - even though there's a lot more to learn.
     
  10. Write4U Valued Senior Member

    Messages:
    15,852
    Unpacking 13.8 billion years of chemical evolution cannot be accomplished in a few hundred years of advanced scientific research in a 30 x 30 laboratory.
    Hazen estimates the the earth alone has performed some 2 trillion, quadrillion, quadrillion, quadrillion chemical interactions during its 4.5 billion years of existence.
    https://en.wikipedia.org/wiki/Age_of_Earth
     
  11. Write4U Valued Senior Member

    Messages:
    15,852
  12. Write4U Valued Senior Member

    Messages:
    15,852
    Interesting tidbit; An unfertilized egg is not alive. It is a packet of bio-chemicals with insufficient properties to qualify as a living thing. Only upon fertilization is the growth code activated and the process of growth and mitosis self-organizes into a living organism.
     
  13. billvon Valued Senior Member

    Messages:
    19,261
    So you would claim that a skin cell is not alive?
     
  14. Write4U Valued Senior Member

    Messages:
    15,852
    No I would not. A living skin cell is the growth result of a fertilized egg. It is able to divide, one of the requirements of living things.
    and dead skin cells provide food for symbiont bacteria.

    In humans unfertilized eggs are flushed away as a waste product. It's just a bundle of biochemicals. Unfertilized eggs have but one set of chromosomes, they are unable to divide.
    Unfertilized chicken eggs are laid just like fertilized eggs, but will never develop into a living chicken.
    No rooster, no offspring.

    Note: this is a qualified statement.

    Does the slime mold really have 720 sexes?
    https://www.popsci.com/the-blob-slime-mold/#
     
    Last edited: Sep 30, 2020
  15. Write4U Valued Senior Member

    Messages:
    15,852
    And you do know that people feel pain differently than others?
    How do "others" feel pain different than humans? Can you be more specific?
     
  16. Q-reeus Valued Senior Member

    Messages:
    4,083
    Sounds really plausible. Well....just count the caveats. And as usual, many critical issues are never discussed. Knowing in advance all or nearly all the true believers here in purely unguided abiological OOL won't even bother to watch, here is a wake up notice that SHOULD be watched by the same:

    Anyone who does watch is free to critique *objectively*. Some here can't distinguish that from negative rhetoric as conditioned reflex actions.
     
    dumbest man on earth likes this.
  17. paddoboy Valued Senior Member

    Messages:
    27,534
    *yawn* So the origin of life is a complex problem...So?
    Nature/and the synthesisation of the elements inside stars and finally Abiogenesis, had 100 millions of years to overcome those problems.
    Oh, sorry q-reeus, no I did not watch all the video. Suffice to say, you havn't said anything of any value.
     
  18. Q-reeus Valued Senior Member

    Messages:
    4,083
    And the truth of that last line is painfully obvious. Had you watched it all and honestly assessed the points raised, your 'had 100 millions of years to overcome those problems' would likely never had been ignorantly typed out. Tour makes it very clear that time is the enemy of unguided abiogenesis. Too bad that and many other key issues raised and clearly explained, you choose to be blissfully unaware of, or indifferent to. Your choice.
    And you have? I merely pointed to Tour who it is that gives a true expert's critique of a dogma-based hypothesis with many grave weaknesses. And with his qualifications and track record he should know. Refusing to here but a fraction of that account is not smart.
    PS: 'synthesisation' is a nonsense word. Try synthesis. Correct spelling and shorter as well.
     
  19. paddoboy Valued Senior Member

    Messages:
    27,534
    I assessed it just as I have assessed your other thoughts on 9/11 and ghosts and goblins, and your previous ramblings on ID Nonsense.
    Certainly not questioning Tour and his opinion, but that's all it is...his opinion. Conspiracies that you love, not withstanding, and as I said, Abiogenesis had plenty of time to start, somewhere sometime, despite scientists not knowing the exact pathway.
    Plenty of truth in Sagan's old saying, We were born in the belly of stars. Abiogenesis is the only scientific answer to the problem...whether Earth based or Panspermia.
     
  20. paddoboy Valued Senior Member

    Messages:
    27,534
  21. Q-reeus Valued Senior Member

    Messages:
    4,083
    Far from nonsense but you are free here at SF to make such unsupported claims. And how could you have properly assessed what you admit to viewing only a fraction of the whole? Rubbish.
    No, a careful and comprehensive overview born of much experience and training. Having impeccable qualifications in the requisite arena.
    'Scientific' as narrowly defined by a materialism-only-allowed dominant world view. And wholly inadequate on many levels as convincingly explained in that vid. Tour himself does not identify with ID although is sympathetic to it's aims. Interesting.
     
  22. Q-reeus Valued Senior Member

    Messages:
    4,083
    You could hypothesize countless trillions of years in some wholly artificial prebiotic scenario involving zillions of planets all sustained in ideal 'goldilocks zones'. Tour explains why life would never take hold even there by purely natural processes. You have absolutely no feel for the many cascading obstacles getting in the way.
     
  23. exchemist Valued Senior Member

    Messages:
    10,147
    Aha, James Tour. A well-known actor in the creationist charade.

    I'm not going to watch a 22 minute video by this character, but I did read, earlier this year, this written piece by Tour: https://inference-review.com/article/animadversions-of-a-synthetic-chemist. which I reviewed on another forum as follows:

    " Oh God , not James Tour again.

    This guy has done no work in abiogenesis research and simply trots out the Disco 'Tute party line, apparently because he is a Messianic Jew with a religious axe to grind. There is no scientific argument in anything he says about the origins of life and he has done no relevant research in the field.

    All Tour can do is produce another version of the Argument from Personal Incredulity, dressed up with irrelevant bits and pieces of science. This article consists of pages and pages of irrelevant stuff about molecular motors etc that he has worked on, which tell us nothing about abiogenesis at all. And at the end he makes only 2 points:

    - It is all terribly difficult to do in the lab. [Well, what a surprise. In the lab. On the timescale of the career of one Houston academic chemist.]

    - Science does not know how abiogenesis occurred. [Er, we are all well aware of that.]

    However, because he includes masses of detailed - and irrelevant - synthetic chemistry about his molecular motors etc, he can bamboozle people who don't know any chemistry into thinking: "Gosh this guy seems to know what he's talking about: it must be a knockout argument".

    However, if one does know a bit of chemistry, and is not fazed by loads of pictures of organic molecules, one finds after ploughing through this article that he has nothing new to say!"


    I also, on another occasion, reviewed a video of a talk Tour gave to a Baptist seminary, in which he misrepresented the work of a scientist called Szostak. My comments were as follows:

    " Just watched part of this and it is quite shocking.

    There is no question that Tour was playing to the audience (of Baptist theologians*) by deliberately misrepresenting what Szostak was saying.

    - He lied by falsely claiming that Szostak's article in Nature was a research paper when it was a cartoon summary for a bit of light relief and clearly marked as such.

    - He lied by falsely telling his audience that glyceraldehyde: Glyceraldehyde - Wikipedia is not a simple sugar

    - He lied by claiming ribose linked to a cyclic heterocyclic base was not a potential building block for an early RNA molecule.

    He had a lot of fun with the audience, who naturally lapped it up, as it is what they wanted to hear. But an alert undergraduate chemist in the audience would have immediately spotted the misrepresentation.

    It seems plain that Tour is, as I suggested in an earlier post, driven by the religious axe he has to grind to connive in spreading falsehoods, exploiting his status as a chemist to fool people who are in no position to challenge him. It is rather a disgusting exhibition."

    There is no reason to treat Tour as an authority with any credibility on the subject of abiogenesis.
     

Share This Page