Chemical evolution:

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

  1. paddoboy Valued Senior Member


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

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    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.
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    the paper:

    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.
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  3. pluto2 Valued Senior Member

    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.
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  5. Beer w/Straw Transcendental Ignorance! Valued Senior Member


    It may be truth. You should investigate.
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  7. exchemist Valued Senior Member

    Thank you, Eeyore.

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  8. sideshowbob Sorry, wrong number. Valued Senior Member

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

    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

    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.
  11. Write4U Valued Senior Member

  12. Write4U Valued Senior Member

    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

    So you would claim that a skin cell is not alive?
  14. Write4U Valued Senior Member

    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?
    Last edited: Sep 30, 2020
  15. Write4U Valued Senior Member

    And you do know that people feel pain differently than others?
    How do "others" feel pain different than humans? Can you be more specific?

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