Stories
Slash Boxes
Comments

SoylentNews is people

posted by martyb on Monday October 07 2019, @03:18PM   Printer-friendly
from the sooooo-close,-but-not-quite-there-yet dept.

Single reaction mixture can produce all four RNA bases

There's a strong consensus that life on Earth got its start through RNA[*], a close chemical sibling of DNA[**]. Over the last few decades, researchers have described how individual RNA bases can spontaneously polymerize, forming longer chains that could ultimately catalyze key chemical reactions, including building even longer RNA molecules. As a result, it's clear that RNA can perform two functions: carrying heritable genetic information just as DNA does and carrying out the instructions encoded by that information.

There's far less agreement, however, on how those RNA bases themselves first form. These bases have a combination of one of two types of flat, ringed structures linked to a small, ring-shaped sugar. Over time, researchers have found sets of chemical reactions that could start with simple chemicals likely to be found on the early Earth and end up with one of the three more complex chemicals needed to form RNA. But the conditions needed for these reactions weren't compatible, raising questions about how an RNA molecule could ever form from these reactions.

Now, a group of chemists has figured out a way to form the portions of RNA that give it its identity starting from a simple set of chemicals. The work relies on materials that can easily be provided by a volcanic environment. And driving the reactions forward requires little more than a few wet/dry cycles.

[...] In the end, the authors tested a series of separate reactions that produced each of the four bases from an identical set of starting materials but requiring different intermediates for each reaction (things like iron, a specific mineral, and so on). Then, satisfied that it worked, the researchers put all the intermediates in a single pot and were able to show that the final mixture contained all four bases. That's the first time this has ever been demonstrated.

That said, it's not a complete solution, as the final reaction involves a sugar that has to be provided separately. While there are known ways of making sugars from equally simple starting materials, those methods require conditions that aren't compatible with these reactions. So we still can't make an entire RNA molecule starting with simple conditions.

The conditions also aren't entirely simple, as there are a number of reaction intermediates that must be supplied. In addition to the iron, zinc, and a mineral called lüneburgite, there are things like urea and a source of sulfur-hydrogen bonds. While it's plausible that all of these things were available on the early Earth, there will undoubtedly be some discussion about whether they were present in the same place and under the requisite conditions. And there's the issue of the fact that the sugar needs to be provided separately.

All of which is another way of saying that this doesn't completely solve the question of how life could arise from simple precursors. But that doesn't take away from the authors' accomplishment: "We show that the key building blocks of life can be created without the need for sophisticated isolation and purification procedures of reaction intermediates that are common in traditional organic chemistry."

Science, 2019. DOI: 10.1126/science.aax2747.

[*] RNA: Ribonucleic acid (RNA):

Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and DNA are nucleic acids, and, along with lipids, proteins and carbohydrates, constitute the four major macromolecules essential for all known forms of life. Like DNA, RNA is assembled as a chain of nucleotides, but unlike DNA it is more often found in nature as a single-strand folded onto itself, rather than a paired double-strand. Cellular organisms use messenger RNA (mRNA) to convey genetic information (using the nitrogenous bases of guanine, uracil, adenine, and cytosine, denoted by the letters G, U, A, and C) that directs synthesis of specific proteins. Many viruses encode their genetic information using an RNA genome.

Some RNA molecules play an active role within cells by catalyzing biological reactions, controlling gene expression, or sensing and communicating responses to cellular signals. One of these active processes is protein synthesis, a universal function in which RNA molecules direct the synthesis of proteins on ribosomes. This process uses transfer RNA (tRNA) molecules to deliver amino acids to the ribosome, where ribosomal RNA (rRNA) then links amino acids together to form coded proteins.

[**] DNA: Deoxyribonucleic acid:

Deoxyribonucleic acid (/diːˈɒksɪˌraɪboʊnjuːˌkliːɪk, -ˌkleɪ-/ DNA) is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids; alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by PartTimeZombie on Monday October 07 2019, @10:10PM (3 children)

    by PartTimeZombie (4827) on Monday October 07 2019, @10:10PM (#903869)

    It's true. I am hard to please. And old and grumpy.

    Also, I think the football* team I support might be about to pay too much for a player we don't really need who has a history of bad knee injuries.

     

     

     

    * "Football" in this case being proper football, the type played in Australia, below the Barassi Line. [wikipedia.org]
      Because I live in New Zealand, I can't find anyone who cares.

    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2  
  • (Score: 2) by c0lo on Monday October 07 2019, @10:23PM

    by c0lo (156) Subscriber Badge on Monday October 07 2019, @10:23PM (#903876) Journal

    * "Football" in this case being proper football... I can't find anyone who cares.

    Bad luck in this case again. I used to unenthusiastically watch soccer in my youth (while still living in Europe).
    Immigrating in Australia had the additional benefit for me of not having to pretend I like any type of football anymore and this without causing raised brows.

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
  • (Score: 2) by Thexalon on Tuesday October 08 2019, @01:59AM (1 child)

    by Thexalon (636) on Tuesday October 08 2019, @01:59AM (#903931)

    Because I live in New Zealand, I can't find anyone who cares.

    But I'm guessing there are a lot of people going wild for the All-Blacks right now, what with their top showing so far at the Rugby World Cup. That's a way more entertaining football than, say, the variety played by us weirdos from America.

    --
    The only thing that stops a bad guy with a compiler is a good guy with a compiler.
    • (Score: 2) by PartTimeZombie on Tuesday October 08 2019, @02:08AM

      by PartTimeZombie (4827) on Tuesday October 08 2019, @02:08AM (#903933)

      Yes, we're all going mental about the All Blacks, which happens every 4 years.

      If we fail to win the World Cup, we're all going to chip in and buy a nuke off a bloke called Kim that Dave knows and we'll use it to commit suicide.

      Rugby is taken seriously here.