Earlier quoted context omitted.
Yep, you are 100% correct. In fact, it is much more likely they were originating on Earth itself than a random hobo asteroid. > The missing part is how do they form self-replicating mechanisms capable of evolution. Well, there are some missing parts, yes, but RNA can self-replicate already; at the least some RNA can. Ribosomes also contain RNA so its is a ribozyme.
RNA can replicate in highly artificial conditions that would seem to already require life to occur.
Ryugu asteroid samples contain all DNA and RNA building blocks
121–130 of 180 posts
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#122That's not really new. It seems as if some people try to project "there is life outside of planet Earth". Well, the thing is ... is this question important? You already have life here. Synthetic biology will also progress. So why is it important if life is anywhere else? I don't understand it. There is nothing magic in RNA or DNA. Granted, right now we can not easily explain how life gets "bootstrapped", but recently…
Why study anything new? You survived this far without it, after all :)
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#123Earlier quoted context omitted.
So you survived re-entry. Now, you get to survive impact. Seems like the energy released would also be damaging
Most asteroids have slowed to terminal velocity by the time they impact. It’s not nothing, but it’s mostly going to be relevant to physical processes and not chemical ones. You might consider that scientists advanced enough in their field to be launching missions to retrieve dust from asteroids are actually aware of basic facts relevant to their field of study.
You might consider that even concepts like plate tectonics (which frankly are incredibly obvious if one just looks at a map) were considered ridiculous ideas by the most advanced experts in their field at one point. A point not that long ago.
I’m not saying the person you are responding too is right - but appealing to authority on something like this has a pretty bad track record.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#124Earlier quoted context omitted.
> Atmospheric entry (if that's what you mean) is irrelevant. I think the OP meant that Earths magnetic field and atmosphere shields any terrestrial matter far more than than a bare asteroid that has no such protections, so it seems implausible at first glance that these things would develop or survive in open space rather than here.
> it seems implausible at first glance that these things would develop or survive in open space rather than here. I don't think "organics developed in the vacuum of space" is implied. Survived? Well we have samples now confirming, if I'm understanding the basis for the discussion (the article).
We have some organic ‘building block’ compounds confirmed frozen on some asteroids.
But what we don’t have is any examples of them surviving re-entry.
We also have a massive amount of those same compounds already here on the planet.
Causality is… tenuous. But not impossible.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#125Earlier quoted context omitted.
Huh? Those smaller rocks would be even more irradiated, as they have no atmosphere? They’d also have to contend with re-entry.
Meteorites are generally cold when they reach the surface of the earth. The heat of reentry is very brief and generally just on the surface. That's my understanding.
The surfaces are typically melted - the ones that don’t just explode anyway.
Icy meteorites never survive re-entry that I’m aware of; and most carbon/chondrite ones don’t either, but they are the most common type that do. They tend to be ‘dry’, however.
Re-entry is a very ‘angry’ process.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#126Earlier quoted context omitted.
ty ty! I usually just give a quick chatgpt buy my work blocked every ai but copilot
Please don't just post slop anyone else could have gotten from AI. It undermines the entire purpose of this site, and reduces the quality of discourse drastically.
GP probably meant he would've relied on chatgpt instead of the help of a kind user to get the same info, not that he would actually post it here.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#127Ummm ... the "Victoria University of Wellington in Australia"? Please. Victoria University is located in Wellington, New Zealand [1]. Nothing to do with Australia. Dr. Morgan Cable is a Senior Lecturer in Space Science at Te Herenga Waka, Victoria University of Wellington in New Zealand [2]. Can't believe that phys.org would publish such an error. [1] https://www.wgtn.ac.nz/ [2] https://www.psi.edu/staff/profile/morg…
First time I’ve seen my university mentioned online and it’s the wrong country!
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#128Earlier quoted context omitted.
I mean, Multi worlds is the only way this impossibly random event can occur on its own.
That's not true. If life has the odds of one in a quadrillion of happening, and we're here to discuss it, then we're that one in a quadrillion . If we weren't, we wouldn't be alive. By definition, we were the lucky ones with the perfect conditions that resulted in us.
That is what I meant.
But I don't think we are "lucky", because we are part of the world, not something that was placed inside it by choice. It is like asking why is Nile in Egypt and not in some other place. If Nile is in some other place, it would not be Nile...So does it make sense to say that Nile is lucky to be in Egypt? No, I think it does not make sense...
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#129Earlier quoted context omitted.
Parts of the RNA world theory are correct, but other parts are completely bogus and completely illogical. What is correct is that RNA must have existed a very long time before DNA, during which RNA was the only nucleic acid. Moreover, self-replicating RNA must have existed before ribosomes and proteins (where "protein" means a polypeptide that is synthesized using a RNA template). It should be obvious that neither ri…
>However, any RNA-based catalyst could have appeared only at a later time after the establishment of RNA self-replication. RNA by virtue of its biochemistry is capable of self replication already. Sequence affinity alone is sufficient to drive structure formation. But without a template, structure can also form on its own (example of an open access paper exploring one such mechanism under certain conditions, 1). This…
Nope.
RNA is not capable of self replication. RNA by virtue of its biochemistry is only capable to be used as a template for replication, but the copying of the template must be done by a different molecular machinery.
If you put almost any RNA molecule in a jar together with monomers, you can wait until the end of time to see its replication.
Normally, RNA can be replicated only by a special enzyme, a RNA-dependent RNA polymerase. This kind of protein is used by many viruses.
It is hypothesized that a RNA molecule with a very special structure might have been used in the beginning as the catalyst for template-controlled polymerization, instead of a RNA-dependent RNA polymerase, to ensure self-replication. Some experiments have suggested that this is indeed possible.
Only after a self-replicating RNA molecule already existed, or if a RNA molecule existed in combination with a RNA polymerase that was produced by other means than by using a RNA template, other RNA molecules with various other functions could appear, and they would have been replicated by the already existing mechanisms, so they would be inherited by the descendants of a living being.
The link provided by you has nothing to do with RNA replication.
It describes a mechanism for the polymerization of nucleotides, which produces random nucleic acid molecules, not molecules that replicate an existing template.
A chemical reaction of this kind is what must have existed before the appearance of a self-replicating RNA molecule. Among the many random polymers produced before that, there was eventually one capable of self-replication, which started the evolution of genetic information.
This kind of reaction is what I have referred to as "side reactions" that happened during the use of ATP and of the other nucleotides as energy sources for the polycondensation reactions used in living beings to make macromolecules.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#130Earlier quoted context omitted.
Life cannot appear in any of the small bodies that become meteors, because there is no source of energy for it. Life can appear only on big planets or on big satellites, like the big satellites of Jupiter and Saturn, if they have a hot interior and volcanism. Volcanism brings at the surface substances that are in chemical equilibrium at the high temperatures of the interior, but which are no longer at chemical equili…
>Solar energy cannot be used for the appearance of life. Capturing light requires very complex structures that can be developed only after a very long evolution and which cannot form spontaneously in the absence of already existing living beings. I think that is putting the cart well before the horse. Earliest "life" I would say looks something like a short sequence of random RNA, in some structure (as in secondary),…
Not true.
What you describe is a perpetuum mobile.
No kind of life can exist without a continuous flux of energy. The formation of any organic polymers requires energy, it cannot happen spontaneously.
Nucleotides that collide do not form polymers in water. The polymerization of nucleotides and of amino-acids and of most other organic macromolecules is done by water extraction (a.k.a. polycondensation).
Water extraction inside water requires considerable energy (i.e. you must dry some thing while it is still submerged in water). This is provided by certain dehydrated molecules, like ATP, from which water must have been extracted as a result of capturing some energy from the environment.
The common ancestor of all living beings known on Earth obtained energy by the reaction between free hydrogen (dihydrogen) and either carbon monoxide or carbon dioxide. It is likely that the capability to use carbon dioxide has appeared later and the very first living beings were powered by the conversion of dihydrogen and carbon monoxide into acetic acid. The energy from this reaction was captured because the first result of the reaction was not free acetic acid, but acetic acid condensed with another molecule, like in the acetyl-CoA that is used today by all living beings. Than that condensed molecule could be used to extract water from other molecules, producing dehydrated molecules like ATP, which can be used for the polymerization of nucleic acids.
There is no way to circumvent the need for a continuous source of energy for the appearance of life. Besides the H2 and CO gases, there was an alternative source of energy that was used very early, but it is not known if it was already needed for the initial appearance of life or it began to be harvested at a later stage. This second source of energy is the difference in ionic concentration between the acidic water of the primitive ocean and the alkaline water that is produced by dissolving volcanic rocks in places like hydrothermal vents, where H2 and other gases are also produced. The ionic concentration gradients produce ionic currents, which can power certain chemical reactions, like they also do in all present living beings.