Certain molecules exist in two similar forms that are symmetrical mirror images of each other: they are known as chiral molecules. On Earth, the chiral molecules necessary for life, mainly amino acids and sugars, exist in only one form
Certain molecules exist in two similar forms that are symmetrical mirror images of each other: they are known as chiral molecules. On Earth, the chiral molecules necessary for life, mainly amino acids and sugars, exist in only one form - either the left-handed form or the right-handed form. Why would life "choose" in the first place in only one of the two ways?
A group of researchers from France managed to obtain, for the first time ever, an excess of "left-handed" molecules (and then also an excess of "right-handed" molecules) under conditions that mimic those existing in interstellar space. This finding strengthens the hypothesis that the symmetry of biological molecules found on Earth originates in outer space. The researchers also hold the opinion that the solar nebula (the term in Wikipedia) was formed in the region of heavy stars. The research findings were published in the scientific journal The Astrophysical Journal Letters.
Chiral molecules are molecules that exist in two similar forms (enantiomers) that are symmetrical mirror images of each other, one is "right-handed" and the other "left-handed". For example, our two hands are an example of chiral structures because they exist in two forms, the right and the left, the symmetrical relationship between them is like mirror images, and they overlap only when we place them opposite each other and not one above the other. Most biological molecules are chiral, with a preference for one form out of several possibilities (two, or more).
For example, the amino acids that make up proteins exist in nature only in one of the two possible enantiomeric forms - the left form (L). On the other hand, the sugar molecules present in the DNA helix of living beings exist only in the right-handed form (D). This property, in which organic molecules of living things exist in only one of their structural forms, is called homochirality (the term in Wikipedia).
What is the origin of this symmetry in biological systems? Today, two competing hypotheses are prevalent in the world of science: the first assumes that life was created from a mixture that contained 50% of one enantiomer and 50% of the other enantiomer (a mixture known as a "racemic mixture"), and that the homo-chirality property emerged gradually during evolution. The second hypothesis assumes that the asymmetry that led to homo-chirality preceded the appearance of life, and originates in outer space. This hypothesis is supported by the observation of an excess of the L-form of certain amino acids isolated from ancient meteorites. According to this scenario, these amino acids were formed non-racemically in interstellar space and were brought to Earth by meteorites and comet particles.
In order to further strengthen this hypothesis, the researchers first prepared analogs of interstellar and cometary glacial particles in the laboratory. The innovative aspect of the research was that the particles were exposed to polarized ultraviolet radiation, simulating the conditions that existed in certain space environments. When the particles were heated, organic precipitates formed.
A comprehensive examination of this mixture revealed that it contains a significant enantiomeric excess of one chiral amino acid - alanine. The excess rate, which was over 1.3%, is similar to the rate measured in ancient meteorites. In other words, the researchers were able to create, under conditions similar to those that exist in outer space, asymmetric molecules that exist in the living world from a mixture that did not contain chiral substances. This was the first time that the scenario explaining the origin of this asymmetry was practically demonstrated in the laboratory through an experiment in which a completely natural synthesis occurred.
These findings strengthen the hypothesis that the origin of homochirality is in outer space and that it preceded the appearance of life on Earth. According to this scenario, the emergence of organic matter from outer space containing an enantiomeric excess, created through an asymmetric astrophysical process (in our case, polarized radiation), is the source of the asymmetric shape of the molecules of life on Earth.
It is even possible that this material was formed outside the solar system. In addition, the researchers claim that the solar nebula originates from regions of space where heavy stars were formed. In these areas, ultraviolet radiation polarized in the same direction as the radiation used by the researchers was observed.
In conclusion - these findings imply that the choice of one enantiomer over the other among the molecules of life found on Earth is not the result of chance, but originates from a defined physical mechanism.
24 תגובות
Even if you repeat the nonsense a thousand times, it will not turn into a serious sentence.
Note that in gematria "The Name" (the God of Tzvitsikowitz) is equal to "The Name" (turned into a wilderness (the minds of those who believe in Him))
Note that in Judaism it is written "this versus that made them" a bad creation versus a good creation God's worship tilts the scale to good an excess of "left-handed" molecules (and then also an excess of "right-handed" molecules), this is our choice
The simple answers are with us, you just have to connect and listen. It's a shame for such a large investment in money and resources that can serve many needy people, God is with us all
Note that in Judaism it is written "this versus that made them" a bad creation versus a good creation God's worship tilts the scale to good an excess of "left-handed" molecules (and then also an excess of "right-handed" molecules), this is our choice
We have the simple answers, just connect and listen, it's a shame such a big investment in money and resources that can serve many people in need, God is with us all
Answer to commenter number 2 - different enantiomers are very important in the pharmaceutical industry. Sometimes (usually?) only one enantiomer will fulfill its "medicinal role" while the other will not and will not even harm.
So now one must try to find places in space where there are conditions similar to those conditions that created this type of molecules from which a similar biology is likely to have been created and where a project like "Sty" will likely have a better chance of finding something.
Michael,
You are right - what is important is that the chirality is not random and therefore there may be some natural preference.
deer:
I'm not sure that a preference for left chirality has been proven.
In fact, it was reported that they managed to create conditions in which more left-handed chirality is created and then they also managed to create conditions in which more right-handed chirality is created, where both types of conditions are ones that can prevail in space.
In fact - what has been proven is that the chirality is not completely random and depends somewhat on the environmental conditions.
Completing Michael's words
I think there are two questions here:
One question is whether there is a natural preference (in space) for molecules with a certain chirality. On this (if the research is correct) it seems that the answer is positive - because the result is significant (1.3% is a statistically significant result for more than 4^10 molecules and there is no dispute about that).
The second question is whether this natural preference is significant to the biological preference - and here I think I agree with Michael that the answer is negative - why? Because even though there is a preference, it is very small and therefore hatred is not significant. The fact that something is true does not mean that it is significant and sometimes it is simply better evolutionarily to choose right or left and it doesn't really matter what is chosen.
Yoel Moshe:
You understood my words correctly and I really think that the discovery has no critical effect on understanding the origin of life.
If someone thinks otherwise, they are welcome to explain it in detail because I don't see how the difference of 1.3% has any effect (and its statistical significance is of no importance. This significance, if it exists, contributes to the reliability of the experiment but not to the understanding of the origin of life).
The authors of the article can be understood.
The question about chirality came up at some point and they went looking for a possible source for it.
They discovered an interesting chemical/physical phenomenon but every phenomenon seems more interesting when you relate it to the origin of life.
To Michael and Eliyahu sorry but I remained confused. If I take Michael's explanation according to which the left chirality was simply lucky to fall within the initial creation of the first living cell, then the percentages do not change. Even if the left chiral marker was only 10% of the probability if luck fell on it then it is the winner. On the other hand, the article and Eliyahu attribute this to a statistical feature that gives an existential advantage.
I'm still looking for clarification and thanks again in advance
to Yoel Moshe,
A difference of 1.3 is significant, because apparently it is statistically significant.
(according to a statistical test conducted)
Yoel Moshe:
Not sure an explanation is needed.
There is a phenomenon commonly called Frozen accident
This is the phenomenon in which Microsoft's operating system and not Apple's became the standard.
At a certain critical moment, Microsoft was lucky (Bill Gates' mother worked at the right time in the right place) and Microsoft's operating system conquered the world even though Apple was better.
Similarly, one might think that left-handed chirality was so lucky when it was incorporated into the first living cell. It is possible that amino acids of both types cannot act together and create life, therefore the luck of left-handed chirality in the first living cell already dictated that all amino acids in living things would be left-handed, just as it also dictated the result that all sugars used by life would be right-handed (I don't know enough biochemistry to determine That's for sure. Maybe Camila or R.H. can contribute something to the topic).
After we manage to create a completely synthetic living cell (nowadays we only know how to synthetically produce DNA) it could be interesting to try to create a living cell with reversed chirality. I think it can work.
Please understand friends [Zvi-Racha Rafaim-Michael Rothschild] and without arguing please explain simply how a variance of 1.3% that if I translate it into a ratio = 48.7/51.3 becomes total control of one of the parties? Why wasn't the 48.7/51.3 ratio maintained throughout?
Thanks in advance for any explanation and good night.
But beyond the appearance - the cat molecules also have reverse chirality, so maybe the milk is good after all
An article about the chirality of the molasses mentions again the anecdote about Lewis Carroll's trial in his book "Through the Looking Glass"
"How would you like to live in
Looking-glass House, Kitty? i
wonder if they'd give you milk
in there? Perhaps Looking-glass
milk isn't good to drink…”
And the answer: the milk will indeed not be good for the cat due to reversed chirality.
א
You have already proven in other discussions that all you understand about the probability is: 50% (sometimes you also write 49%)
Please stop bothering.
Lezvi-how is it significant if the mixture is serial? After all, even if there are a trillion molecules, the ratio will still be almost 49% for the preference of a certain enantiomer. This is nothing.
A preference of 1.3 percent (about 1/100), is significant in the case that the sample is larger than 2^100.
Under the assumption that what they say is a "comprehensive test" the researchers tested over 10,000 molecules (and it is very likely that this was the case because it is really, really not a lot in relation to the number identified), then the preference that was discovered is not accidental.
"A group of researchers from France managed to obtain, for the first time ever, an excess of "left-handed" molecules (and then also an excess of "right-handed" molecules) under conditions that mimic those existing in interstellar space. This finding strengthens the hypothesis that the symmetry of biological molecules found on Earth originates in outer space."
The finding is at best correlative. The fact that in space or in space-like conditions there is an excess of one or another enantiomer does not under any circumstances mean that the enantiomeric source here in Israel is in space. A very serious mistake by the writer of the column or the writers of the article. It is possible that a common mechanism is responsible for the selection, why jump to the (more attractive) conclusion that the origin of the molecules is from space?
An excess of 1.3 percent? That's absolutely nothing. According to the hypothesis of the RNA world, the primitive molecule was quite long, because it is also supposed to code for enzymes. It still seems like a slim chance...
Interesting news, thanks.
Some Comments:
1. The links are missing.
2. If I understood the article correctly, then in the sentence "This finding strengthens the hypothesis that the symmetry of biological molecules found on Earth originates in outer space" the word "symmetry" should be replaced by "a-symmetry". This error appears several more times, confusing the reader (or did I not understand?)
3. In my opinion, there is a problem with the artificial separation between the environment of "outer space" and the ecosphere (before the formation of life) and the biosphere, since where did the solar system and the earth rotate, if not in "outer space"?
I bother about this matter, because I find in it hints of exogenous theories, regarding the origin of life (in the sense, "We found the origin of life: in outer space!"), which seems to distance the solution to the question.
This may tip the balance towards deciding which enantiomer will be chosen in the end (right or left) accordingly, but it is still important to remember:
The reason that biochemistry is chiral is simply because of the enzymes:
They are the ones whose spatial form is able to work only with a single enantiomer. Which one of them ? It probably depended on the initial conditions mentioned in the article.
And it is enough that there was a preference of a few percentages towards Masneim, he became dominant.
By the way, this question is quite similar to matter and antimatter:
Why did nature choose matter when in the big bang an equal number of matter and anti were created.
There the answer is symmetry breaking, but in my opinion there is no answer as to why "precisely" the material was chosen.
One can get an example of the difference in the characteristic of life that is expressed due to the replacement of a right-handed molecule with a left-handed one.
There was an article here not long ago about a plant in the American West whose DNA segment transformation manifested itself in being
Perennial/annual and during its flowering period.
Interesting, but I didn't buy it.