Why is life left-handed? We might finally know
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- Опубликовано: 21 мар 2024
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Everyone knows the classic double helix-shape of DNA, but no one knows why the DNA twists one way and not the other. Scientists have been trying to figure out why organic molecules have the particular orientation that they do - this so-called “handedness”. It seems like one of those questions that we'll never answer, but to my surprise recently there's been some progress on answering the question.
First Paper: onlinelibrary.wiley.com/doi/1...
Second Paper: www.nature.com/articles/s4146...
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An interesting but troublesome detail: the thalidomide molecule can switch chirality in the body, so it’s not sufficient to separate out the ‘correct’ enantiomer.
Oh dear, I didn't know that, thanks for the info!
Yeah. It can spontaneously switch chirality. The solution eventually turns into rasemic mixture regardless which composition of enantiomers it had in the beginning.
Thalidomide racemizes in physiological conditions spontaneously.
i vividly remembered my old chemistry teacher mentioning that in class
That is a really interesting point!
I appreciate how you said "as i understand it." You're always clear when you aren't an expert on something and try to let us know when you have a bias on something instead of simply acting like it's a universally held belief. Thank you!
DNA is not left handed. Yet she shows some left handed DNA, says it is proper DNA. Then she flips the axis so that the DNA models is actually correct, but then she says the handedness is incorrect. Why are Scientists are SO FING DUMB that the don't even check the handedness of their models before dis-educating the public. That or it is defiantly some treasonous Mockingbird mal-education afoot. In either case. UNDERSTAND HOW TO CHECK HANDEDNESS YOU 1984 CHUMPS! or you wonk know anything but what the system tells you! Not one person here is checking her work!
Glad to see someone noticed one of the many reasons she gained my respect!
I think it is important to clarify a few things:
When we talk about life being left-handed, we talk about amino acids. (The sugars of RNA and DNA as well as their helices are, indeed, right-handed). All of this is, of course, purely definitional. So, if we did meet an alien life-form, it would be quite useless to determine the handedness of their biochemistry, unless theirs was also made up of aminoacids and nucleic acids...
To me at least, the fact that all life forms on earth have the same handedness, use the same 20 or so amino acids etc. in their chemistry, seems to show that they all have a common ancestor. This video implies that if the handedness were to be completely due to chance, there should be some regions left on earth where the opposite handedness predominates. However, this is not the case if life only came into existence exactly once. (Two caveats here: Even if some kind of viable life had happened more often, the lifeforms that were created "first" would have an evolutionary advantage and might have driven the newcomers to extinction. Also, it might be possible that there *is* another microbiome based on another kind of chemistry somewhere in the ocean that we simply haven't found yet because it doesn't interact with the organisms that we do know...)
Due to the self-replicating nature of RNA, once one small molecule of it were formed, it is conceivable that only ribose molecule of one handedness could attach to it, leading to a complete replication of the chirality. It doesn't seem unlikely that such a molecule might have formed by chance, but it is possible (although I'm very sceptical) that its creation might be due to a accumulation of one ribose enantiomer on a magnetic rock. It seems very unlikely to me that with these effects being so small, the Earth's magnetic field might actually be an evolutionary advantage for left-handed over right-handed life.
Yeah it's obvious that it's just because we all share a common ancestor.
I'm inclined to agree. Life is the way it is because of evolutionary pressure. Somewhere along the line 'left handedness' gives a strong advantage.
@audiodead7302 I think you may have misunderstood me. I do not think that left-handedness gives an evolutionary advantage over right-handedness per se.
If life capable of reproduction and survival only came into existence once, then it will have just been left-handed by chance. The concept of an evolutionary advantage only really makes sense if there's someone you're competing against, but of right-handed life just never existed, it is irrelevant.
One concern I’d have with leaving randomness as a source is that the chemistry for forming homochiral structures is very complex. Or rather, it requires a lot of purity and it’s difficult to imagine very complex chains of amino acids forming naturally without something pressuring the chemistry. Maybe relatively simple RNA structures could have done it, but it’s quite a stretch to me. Structures that regulate this in living cells, ribosomes, etc., require codons in the RNA/DNA, so it’s kind of a chicken and egg problem. That’s why I think assuming magnetism might have played a role is promising. An interesting approach would be to try to synthesize a simple RNA-esque molecule out of right-handed chirality components. Perhaps that’s been or is being tried experimentally, but it would seem prudent to answer if right-handed RNA type structures are even possible.
@reedbern In proteins, structures like alpha helices and beta sheets rely on all the amino acids having the correct handedness, because they are stabilised by hydrogen bonds between amino acids that would break down if the substituents of that amino acid were in a different place. I'm not sure if these kinds of order could even be achieved if some amino acids were D and others were L. Also, in early biochemical pathways, one amino acid might be synthesised from another, with retention of stereochemistry.
Thalidomide switches chirality spontaneously in solution, so that when you recrystallize an enantiomerically pure sample, it becomes a racemic mixture once again.
I am a metal worker and often get "fresh made steel" to work on. But when there are older lengths of steel coming into the workshop I notice a distinct magnetic polarization in the steel, that no doubt originally was neutral, when it was "fresh". Having a steel bar laying in the same orientation on earth definitely has effect on the magnetic properties of that steel.
Therefore the stones Sabine talks about could in my opinion absolutely have taken on magnetic properties from the earth magnetic field, given they didn't get moved very often, and might have influenced the handedness of the large molecules. I am by no means a scientist, but thought i chime in my two cents experience.
Taking a (non-magnetized) steel bar, orienting it N/S and beating on it with a hammer magnetized it. Experiment done with my grandfather some 70 years ago. So an iron rich rock in an earthquake could do?
@@milantrcka121 it's pretty weird how impact can both magnetize or demagnetize something.
@@DKNguyen3.1415 It is a complex problem. Very roughly, it all depends on the orientation of magnetic domains, local field strength, and crystalline structure. Impact adds enough energy (shaking) for the domains to orient themselves in the prevailing magnetic field orientation (earth field in this case). Heat the ferromagnetic material beyond certain (critical) temperature and it becomes non-magnetic since the thermal agitation energy exceeds any magnetic magnetic force present in the domains. If interested, research it. Fascinating subject.
@@DKNguyen3.1415 basically you are giving some of the magnetic domains enough energy to escape their current state, and when they settle down, they'll align with the external magnetic field because that is a lower energy state. Imagine you have a bunch of weighted dice in a box. The dice would come up sixes if you through them but they don't have enough energy to turn over just lying flat in the box. But jiggle the box hard enough and they'll pop into the air and more of them will land with the six facing up.
Interesting, thanks
(Dr. Sabine quietly shows a graphic of Earth spinning the other way) I see what you did there.
Or; reverse a video to get by the copyright filter -- just like playing a song backwards!!! Okay, no, that was probably Dr. Sabine playing a trick on us.
Everything about this video is reversed, I checked the date but April fools in a little way off! DNA is right handed, not left!
@@jonathanberry1111apparently amino acids are left handed.
That backwards spinning earth has given me a headache.
I'm going to have a lie down and get up an hour or two ago.
@@jonathanberry1111 just b/c you got DNA on your right hand don't mean everyone is doing the same! (joke).
The earths magnatic poles flip constantly such that crust is exposed to both field directions equally and equal amounts of the crustal rocks had their magnetic domains oriented in each direction. So this theory really just pushes the 'randomness' solution back up the causal chain. It would be the randomness of what magnetic orientation the rocks were at in the location where the first complex molecules formed.
Hi,
Pasteur showed that crystals of tartrates, which precipitate out of wine, come in two forms. When they are separated into two piles, one of each of the forms, the forms may be seen to be mirror images of each other. Furthermore, when these are dissolved in water and subjected to a beam of polarized light, the plane of polarization is rotated by the solution, left for one type of crystal and right for the other. This fact allowed Pasteur to propose an explanation for solutions of naturally occurring amino acids which always cause left handed rotation of a polarized beam. This has been expanded to other organic molecules with asymmetric carbons based on the arrangement of the ligands around the carbon center. It’s been a while since I’ve studied organic chemistry, so I no longer remember the rules for assigning handedness based on these arrangements, but one could look them up if necessary. Just incidentally, many of the sugars we metabolize are right handed in this system.
Cheers,
Keith Klein
Professor Emeritus of Biological Sciences
Minnesota State University
P.s. Yes, I do know there’s a lot more to say about this re amino acids etc. But professors need to know when to shut up.
P.p.s. I am skeptical of the magnetic explanation too.
I think I read once that Pasteur was very lucky, because he was working in a cold laboratory, because the splitting effect for tartrates depends on the temperature and vanishes for crystallization from solution at higher temperature (?), where the crystals turn out to be racemic. I could not figure out again, which article mentioned this though. Could be CHIUZ, about the history of this kind of research, maybe.
that is not an explanation as to why (almost) everything in biology is L. It is a description of the mechanism of transposition pieces of information
Ah, the dextro and levo situation has come to RUclips.
I have seen what creative imaginary minds can do with cordiceps fungus. I can't wait to see what they come up with when imagining worlds of dextro chirality
Subscribed! 👍
You "hold" the molecule with its heaviest substituted R group facing away from you. The weight of the R groups facing you is increasing either clockwise or counterclockwise. That's how it works.
Technically, there is a more complicated algorithm for sorting each substituted group into an order, but I've never seen a case where the result is different from the mass ordering.
Weirdly I was thinking about this very thing recently. For what it’s worth, my theory is that chiral quartzes may play a role. They have shown to preferentially bind one enantiomer of alanine over another. While chiral quartzes may be distributed homogeneously on a global scale, they have higher concentrations of left or right handed enantiomers within various geographic regions. Couple this with variable ocean temperatures around the globe, there could have been sites where temperature accelerated kinetics formed significantly more left-handed peptides which might then have been more stable than free amino acids.
Great I’m left handed so I’m in tune with the universe. Thank you
Sinister!!!!!!
I have bought the Galaxy projector on your recommendation, and I have to say, it is very cool :)
I prefer a little CBD in the evening!
Could be wrong but didn't the magnetic poles flip more than once over our 4 billion years. Just Googled it and the last one was 780,000 years ago
It seems unlikely to me that they'd flip just in the period when life emerged.
I think she had an ad to place...
They did many, many times; but if this explanation is correct, this just mattered back at the very beginning, and even then she said nothing about the polarization, only field strength. Once the metabolic pathways were established, handedness should be set. I don't think your cells can copy your left-handed DNA into a right-handed strand with the enzymes it has.
Was thinking the same, and about how so much randomness there is here. However, your comment gave me the idea that if indeed magnetism selected for bio-chirality, then this debate wouldn't be as useless after all: If that is the case, then the dating of the origin of life has to match one magnetic orientation, aka more or less removing half the past as possible times for such event.
Right handed DNA would be anti-DNA and anti-life!
One has to be careful when saying left-handed stereoisomers have come to exclude the right-handed ones. Many bacteria, for instance, synthesize cell envelope components using D-amino acids, whereas they exclusively use L-amino acids as building blocks for all of their proteins (as in the rest of every kingdom of life). Thus, both stereoisomers can coexist in the same organism (although D-amino acids are used only for very specific structures).
Or, to quote Don Lincoln, "Physics is everything!"
Mathematicians shaking their heads looking at this.
Appreciate your dry wit ... keep it going!
Sabine came so close in the Galaxy Lamp spot and now I want to hear her say "Let me show you its features!"
"Everything is physics" Mathematicians: "u wot m8"
I hate this argument. Math is description of reality. Physics is the reality. Math is a virtual function. It is a subset. A religion of purely hypothetical. Physics would exist absent math. Gravity would still function. Math would not exist absent of physics. It would never have been given rise as the chemical bonds in our minds would never have dreamt it up. Hence math is religion. Physics is reality.
And if you want to argue the SCEINCE of physics is a subset of math: Still no. You can observe gravity without math too. And make predictions that thing a will fall without math. In fact a large portion of sceintific observations can be done enirely absent of any math or quantification. Hot things burn and heat things. Cold things are more brittle. Etc etc.
@@olmsfam1 I can also observe that germs cause illness without needing to know any of the chemistry, and therefore without needing to know any of the physics to make predictions like: “if you eat this rotting thing you’ll get sick”. If you’re using that style of argument to say “physics isn’t just math” then you can also use it to say “everything isn’t just physics”
Evil tongues claim that mathematics is not a science, but the language of science.
@@olmsfam1…until you need to quantify it to design (engineer) a useful solution to a given application. Doh!
If any one chirality becomes slightly dominant, it becomes more economical for other life to be the same since it can utilize discarded material from the dominant configuration without wasting energy modifying it in that manner. Pockets of the other chirality would be out-competed and disappear. Ones chirality is a deep rut to dig out of and switch.
IMO, having both in the biosphere is an unstable configuration.
This ties into my idea that almost everything depends on how plant life developed, and it's possible that light polarization would have a selective pressure regarding chirality for stuff like chlorophyll in terms of efficiency. (I'm probably not the first to come up with it, but it's along lines that could make sense.) In turn that affects which starches, sugars, etc. get made, and there you go...
I would really like to see science news on TV to reach even more people! Science should be made even more accessible to the public.
If this is true then I think one possible follow-on is that the first biomolecules (and maybe the first cells) arose on magnetic rocks like iron ore. Maybe this is also why we use iron as a catalytic center for so many key enzymes? Idk, something to think about.
Why is it in old waste landfills, where metal was buried along with everything humans discard is so much furan, dioxin and similar poisons produced by chemical and biological processes in anaerobic conditions?
According to the British, everyone else drives on the right side of the road, whereas they drive on the _correct_ side. 😊
Also, they live on the unique continent on earth. Everything else is an island.
They just don't want to be in any kind of a "pocket", I guess.
Of course, I should’ve used “whilst” rather than “whereas”. 🤣🤣🤣🤣
Not even being British, there’s some reason to agree. The Romans also kept left and so did Europe until Napoleon conquered it and had his armies keep right to not get stuck behind traffic but rather force oncoming traffic off.
Indeed 🧐
It was really interesting, thank you for all infos.🙏🙏
I'd read an article that suggested chirality was more like the preference of matter over antimatter (as you mentioned -- and even that might still be about magnetism), it's that interactions with the precursor molecules to DNA and other proteins favoring right-handedness with carbons in light from yellow stars. So after a billion interactions, you are left with right-handed precursors -- over time, that adds up. Maybe there is right-handed proteins and left-handed precursors in the light of red stars.
Also, they found that the light coming off Earth is so affected by chirality, that it's polarized more than light reflected off planets without light. So, that's perhaps a good way to increase the odds of life on other planets; look for the polarized light.
Don't I remerber correctly that there were papers some decades ago explaining the handedness of molecules as originating from the broken parity of the weak interaction? At a phase transition, they argued, a system is hypersensitive even to the smallest asymmetries. The left handed molecules are a tiny bit preferred for energetic reasons.
Exactly, that's my preferred explanation. Although I'm not sure if it has been demonstrated experimentally. Rotation of the earth and/or magnetic field should still yield 50/50 or right-handed antipodes.
Why the weak force breaks the symmetry still remains to be answered if you want 'why' to really be answered.
Outside "design," the most plausible explanation is the first primeval replicating macromolecule that displayed enzymatic activity. It would have had a handedness in its catalytic rates.
Since such a molecule spontaneously generating is a fantastically unlikely event, by the time it happened again, the progeny of the first molecule already dominated the entire environment where such abiogenesis was even possible.
I've had similar thoughts of a very rare event (kinetically) preceding a much faster process. Maybe some chiral autocatalytic process that has a huge initial barrier to formation.
Yes. I came down to say much the same thing.
If abiogenesis did happen, it's plausible that it only happened one time. The handedness of that first and only primeval biological particle simply propagated to all subsequent life.
This paper suggests that life's actual favored chirality was more likely to occur because the L-enantiomeric amino acids were far more likely to collect near each other due to the influence of the planetary magnetic field and -- apparently -- nearby ferromagnetic rocks situated near deep-sea volcanic vents.
I actually reviewed a very similar idea to the one you have just made up. It claimed that bubbles in sea water rotate one way in each hemisphere and this could be the reason for DNA chirality, without providing any evidence of that preferred bubble rotation direction (as far as we know, they have none). The problem of the two hemispheres was one I mentioned in the review but not the largest one. Another was wrong dimension scale. But what kills such ideas is that polymerization of DNA does not need it to rotate at all. The polymers can attach to the helices from any direction they like, if they want. The final problem is they do not want at all in sea water as the reaction is thermodynamically unfavorable in such a medium, regardless of its pH (I did a good review of the literature for that opinion as the only reason I reviewed this was my expertise with the bubbles).
It's not exactly what I mean. I worked together with a guy who did microfluidic experiments and showed that shapes with different helicity will travel at different speeds in the flow, depending on how the flow goes. This, so his suggestion, could be used to separate different enantiomers. I agree with you though that the scale is totally wrong. (It's funny though that someone actually suggested this!)
It seems like the "claimed that bubbles in sea water rotate one way in each hemisphere" might have killed the paper. Clockwise and counterclockwise are determined by position of the observer. I also see a problem of scale and think I you are saying scale is off by 2 or 7 orders of magnitude. My guess is without a scale difference of 20 orders of magnitude approximately you are not looking at a useful ration of fuel unit to machine that burns fuel unit. I need the back of envelope and a crayon to convince myself I am not talking out my ass.
@@luck484 The bubbles always travel upwards so position of the observer is not relevant. The rotation will be right in one hemisphere and wrong in the other however we look at it.
Just for fun: As for the "two hemispheres" part, perhaps the universal ancestor of us all, developed, evolved and multiplied in the ponds on the "correct" hemisphere (with "bubble rotations" favorable to the current established handedness) and by the time its descendants overtook the planet, the wrong (unfavorable) hemisphere no longer mattered?! I think that rabbit-hole goes deeper... 😄
@@itsawonderfullife4802 The paper author assumed that the northern hemisphere was the right one because.. he lived there. But jokes apart, it still is impossible because of things I had listed. The DNA (or RNA) chain cannot be created in water because the inverse reaction is more probable (the name of the reaction is polymerization). This is why it is believed this reaction originally happened in ponds which were temporarily drying or freezing. Not in fluid water.
I'M GLAD YOU HAVE A PATRON/SUPORTER. THE GALAXY SEEMS INTERESTING. I ACTUALLY WATCHED ALL OF YOUR SPIEL
Left-handed? Sounds sinister to me.
I saw what you did there beastmasterdexter
Very pun-ey.
Average Americans doesn't understand your joke... Well done
A pun made with a lot of dexterity.
That's a very interesting question. I also heard, that some cosmic factors influence the orientation of organic molecules in space, who, perhaps, are the origin of life on earth. Or the left handedness of neutrinos?🙃🙂
That's an interesting speculation! Start working on your paper :D
@@yerocaUh, unfortunatelly I´m not a physicist, and I don´t want to become one of these megalomaniac crazies. But there already exists a scientific paper on arxiv, that examines the cosmic polarisation in connection with the prevalence of the handedness of organic molecules in space.
@@Thomas-gk42Oh, I thought you might be spit-balling that one.. interesting!
I’ve got to say, I’ve been loving the ~5-10 minute videos! Not that there’s anything wrong with your ~20 minute episodes, it’s rather just that I’ve the attention span of a gnat. I’d be hard pressed to watch a 20 minute video even if it contained the cure for cancer.
They relieve me of the twinge of guilt I feel for all of your wonderful science updates that I’ve been missing :)
My thinking on this is that the first enantioselective self replicating reaction involved one atom. One atom is by definition only one-handed and so this gets propagated through the system.
Biochemist here. It seems much more likely to me that this asymmetry arose by chance. I'll explain:
For life to begin something must have existed that catalyzed a chemical reaction. Today, that's enzymes or ribozymes. And while there are catalyzers that don't care about the orientation of molecules (that's mostly metals), it is very likely that a clump of something formed and started to catalyze reactions. Now a clump of something is likely asymmetrical and this asymmetry means molecules in different orientations will be turned into something else with different efficiencies. If you now take into account that all amino acids get turned into all other amino acids, it makes sense that they'd all be the same (L-amino acids).
And I don't think that the first life outcompeting all the other "almost-life" is unlikely at all. You mention there should be pockets of life with other handedness but for that life must've evolved there, too, and survived competition with "our" life for billions of years...
Most likely random chance. Don’t know if the event originated on Earth, but it occurred somewhere. Most likely occurred at the bottom of the ocean though.
I find this reiterative feedback into one chirality or another most likely. Like a pan full of water balanced on a thin board any slight gain on one side will lead to an overwhelming feedback and 'tip over'.
There's a study that says the beginning handedness promotes its own growth and that might begin in the stellar nursery long before Earth has formed, with deuterium ions as a substitute for hydrogen in a molecule causing the preference of one type of handedness if I remember correctly. Look up 'The achiral key to life'.
The orientation of random clumps being created could be influenced by what they are created by, the majority of such available molecules could be of a particular handedness
Agreed. This is the most parsimonious explanation, to my mind, and is just another consequence of common ancestry.
You are the smartest RUclipsr I have seen in a while you upload very often and with extreme facts
DNA was originally formed in the southern hemisphere, so due to the Coriolis effect, it spins to the left.
(That's just as good as what she said!)
Your talent of explaining things is on another level
4:55 It's actually the other way around. In the old days, since most people are right handed, they would ride on the left so they could brandish the sword against enemies on the right side.
I find it hard to believe, even in ancient times, that people would be so preoccupied with hacking away at oncoming traffic with their swords that they'd organize their traffic patterns to make it easier to do so.
NOT ACCORDING TO THE USDOT-FHA: "New York, in 1804, became the first State to prescribe right hand travel on all public highways. By the Civil War, right hand travel was followed in every State. Drivers tended to sit on the right so they could ensure their buggy, wagon, or other vehicle didn't run into a roadside ditch."
highways.dot.gov/highway-history/general-highway-history/right-side-road#:~:text=New%20York%2C%20in%201804%2C%20became,run%20into%20a%20roadside%20ditch
ya know @JJEHERRERA ... you're on the interwebs ... and it takes roughly ~5 seconds to google something before you make yourself look stupid.
I don't see why there would be pockets of the opposite handedness, since we all evolved from LUCA, there would only have to be an initial role of the dice and whatever came out, stuck.
This is one of those things that's hard to make meaningful: if life benefits from having a common chirality in its molecules, then the fact that we only have one strain to go off of almost nullifies the question. If we found alternative strains(such as native Venusian or Martian lifeforms) and all shared the same chiralities, then that would be an interesting question as to what the advantages are of that specific configuration. If they were to be different chiralities to terrestrial life, then we can study the different environments to (hopefully) determine if it really is just random or if there are meaningful local conditions favoring one configuration over the other.
hahaha. Sabina! Pleasure to spend time with you! As a left-hander I naturally favor levarotatory because I am naturally gragarious and too old to care about my misspelling. BTY I am re-learning how to spell from my grand child. Cheers!
I bought one of those galaxy projectors before you even finished the ad read. I may already own 3 different galaxy projectors... I don't have a problem Sabine, YOU do 😤😜🥰♥️
In almost every chemical experiment, we use stir bars that create currents in the solvent much, much stronger than those in the oceans. Now, granted, we don't let our solutions stir for billions of years... But I promise, if a left- or right-handed stirring of the reaction medium had even a minuscule effect on enantiomer selectivity, we would have noticed...
I believe she was being sarcastic. Oh Lord, I hope she was being sarcastic. 😉
Your experiments don't include submarine volcanoes, hot vents or pirates - gotta watch out for those pirates.
More chemistry content, please!
But it's all physics? 😉
There's a time factor in this too. If organic molecules are forming rapidly, then you'll get lots of both types of handedness. But if they form very rarely, then the first to form and begin self-replicating will spread. And due to being first, it will out-compete any of the opposite chirality which happens to form in the future, effectively killing it off.
Essentially you can think of it as balls dropping down a Galton Board to form a normal distribution, with an added twist that the balls can self-replicate. If the rate at which the balls drop is fairly quick, then it dominates over the self-replication, and you still get a normal distribution. But if the rate at which they drop is a lot slower than the self-replication, then the first ball to drop will replicate a lot in that location. Causing the distribution to skew towards whatever side it happened to drop into, creating the illusion of violating the expected normal distribution.
I've got to hand it to you Sabine, that was a very interesting video! 👍👍😉😉
Everything is Math
Physics is really math. I was just about to post that comment and you beat me to it!
@@ChrisBrengel
Math is really logic
Nope.
Math doesn't always make sense. It's flawed.
@@littlefishbigmountainLogic is just one field of math.
Maybe how to spot aliens amongst us
You added the extra -st in among to protect yourself…
@@herobrine1847 "Among and amongst are synonyms, sharing the same meaning." Internet is your friend.
Technically, "how to spot the aliens among us with 50% probability confidence".
@@herobrine1847 speak for yourself! (joke).
A and B form DNA strands twist in opposite directions, so both left and right are represented. Glucose is D-, or right-handed. Biological molecules are made up of both chiralities, though one usually dominates through a type.
Polarized light from the Sun has also been a proposed mechanism.
Since i studied biology in the nineties that’s what i always wondered!
Thanks!
Mathematically speaking, it is absurd to suggest that life evolved over millions of years while all the right-handed molecules just sat in a corner and then reintegrated without destroying all life.
Unfortunately that is abiogenesis. Find a result that sort of supports the wished objective then ignore all the problems that this finding creates. Every step forward comes with two or three back. Cell biology is no friend, not is chemistry to abiogenesis.
I always knew that I'm right in being left-handed.
that's what you think, in reality your mind mirrors the experience. what is on your left is objectively on your right.
@@milanstevic8424can you please tell me more? I'm left handed and understand none of this 😂
@@sunbeam9222 don't worry it's not your fault, your reality is flipped and it confuses you!
@@milanstevic8424 haha cheers. Definitely forever confused in that reality, me 😂 So for left handed their experience mirror their mind. And for right handed, it's their mind that mirror their experience? That's the theory? I'm past worrying don't worry, I accepted my condition, but still curious
I've always thought it was just chance. But now the right handed rule of torque really blows my mind ...
Several year ago I encountered a study of which explained the brain function and activity in association with our actions and responses:
The brain is divided into two hemispheres… left and right… but the nervous system is ironically connected to the opposite sides:
The left controls the right side of the body… and the right controls the left side… on average:
The left side activities include:
Reading, math, science, memory retention including speed reading, and some also include logic.
The right hemisphere activity includes:
Color, hue (but only women and artists can see): design, dimensions, art, creativity.
During the 60’s scientists via the educational system was pushing children to use strictly the right hand because it interacts with the left hemisphere… in hopes to open and improve students learning skills, but later learned that not all children have that same capability… I was one of those kids… I had a learning challenge.
However I later found my own learning curve… and came to believe though I am not intellectually inclined, but I am more intelligent than most scientists… because I can see the details they can not… of which not everything is based on biology and science.
I have no data to back this up, but one explanation that comes to mind is that the probability for life to start is MUCH lower compared to its ability to spread once it forms. Thus, it just happened to be left handed and spread easily. If right handed sprouts say 200m years later, by then the left handed organism would be far more complex than the newly formed right handed. So right handed gets gobbled up.
A right handed organism would be hard to digest for a left handed organisms, this would give it a big evolutionary advantage.
@@moddaudiothis is likely untrue (at least in some very significant way) as the “evolutionary advantage” would work both directions, which is contradictory. Or at the very least, it would entail an ecosystem of balanced right-and left handed-composed life forms because they both “outcompete” each other.
I just don’t see how that concept is viable
I’m left handed so I’m looking forward to this 😂
Left handed people are the best😊
@@johnvoss2565 after spending my life thinking we were in the minority, this made me smile 😊
I'm forward-handed, so I hope this will be left right behind.
I'm left handed my twin is right handed and our minds are complete opposite 😂
@@sunbeam9222 - Say hi to 2229maebnus for me.
Been awhile since i saw an interesting topic from this channel. Yay!
I think you should put the following timestamps on videos like this:
0:00 Background Information
5:40 New Theory
That way, those of us who are already familiar with this question could easily skip ahead to hear the new development.
I read an article in Scientific American (late 70s) that proposed handedness came about through the interaction of certain clays on some molecules reinforcing a left handed preference.
Me, thinking this was about left handed people.
The only problem with that theory is amino acids and other building blocks of life can be made and found in nature having both left handedness and right handedness in equal quantities. Natural laws produce both varieties with no preference shown at all.
I think you misunderstood the point. The physics doesn't have a preferred chirality, but the biology does. So, there must have been an intermediate step in the chemistry that caused the biology to have that preference. The magnetic rocks provide a step in the chemistry that could provide a selection pressure for a particular chirality.
Some bacteria have the ability to metabolize both chiralities of amino acids, but they still build their proteins from a particular one. If they don't break down the wrong chirality, they have mechanisms to switch the chirality.
@@barontau6552 The point is in the average amino acid chain involves over 300 amino acids. That is 300 to the power of two for life to come into existence by chance. Nature has no way to separate the different sided amino acids and make this choice for life to begin. And these are undifferentiated amino acids not even including a combo that can create a useful protein.
@@anthonycarbone3826 that is just now how probabilities work, and is not a model that is applicable to the subject. These are not all independent random events, the existence of any correlation or anisotropy, which is the very topic of the video, should tell you that is not a feasible model.
@@anthonycarbone3826 "Nature has no way to separate the different sided amino acids and make this choice for life to begin." Unless it can make that choice, of course. The universe is not only made of energy and matter (the belief of all atheists) but also of information and life, being information the most fundamental of all.
Wow.... I read "The Left Hand of the Electron" by Isaac Asimov in 1972 quite a while before I started my journey into chemistry both organic and inorganic. Most chemist with whom I have worked have been cognizant of the importance of chirality in most if not all aspects of their work, included the food scientists who recognized the innovations possible involving it. To hear that there are folks still studying this as basic research and that it sort-of-kind-of sounds like (I have not read the study yet) "Hey.... electrons might have a BIG impact on this!" is VERY interesting. I look forward to the possibility of getting concrete answers "Real Soon Now". (hat tip Dr. Pournelle)
Peaceful Skies.
Was happy to see that I have benefited from your videos. When you started talking about the earth's rotation affecting handedness, red flags flared up in my head. Your clarification was a good laugh. (I did miss the wrong way rotation though - thanks @tscoffeya.)
We all will gratefully acknowledge you in our next paper , Sabine. The title? "Why am I left-handed"
Fun fact, one CAN in fact chirally separate certain molecules via rotational forces of vortices. I too had initially made this idea up offhandedly like you Sabine, many years ago, but upon checking the literature afterwards, I found it to my surprise & delight already documented! Sadly I lost the citation, but it should be easy enough to find
Hello.
It gives an entirely new meaning to Tyrians place as "Hand of the king"
Post script.
Good luck.
I’m a Yank who migrated to Australia. I found the car home absolutely hilarious from the way it was presented. Keep up the good work👍🏻.
No wonder why we dont like each other much,damn those left handed creatures always bump into you when you try to take notes in mach 10.
😂 i like the overlay ad
Yes, the brand actually did the edit themselves, we were all impressed!
Thank you Sabine and the script team, they do not only provide good and rapid content, they also read comments and answer them with broader perspective in their videos.❤
Regarding the weak magnetic field from the earth. Do not forget that we have lightning whose currents can generate a quite strong magnetic field and if it strikes close to a magnetizable rock can leave some quite strongly magnetized rocks behind.
The earth's magnetism is far from weak.
It has an effect on everything.
@@martf1061Its all relative. The earth magnetic field is about 0.5 Gauss but a lodestone field can be over 700 Gauss so more than 1000 times stronger.
@@teamsafa exact. All relative. The earth's magnetism is mesured too far away from where it is generated ( center of earth ) .
There is no other known magnet that can move a compass needle as far from it, like the earth does. I dont know how many Km is the radius of earth, but i know the center is very far from the surface.
And its magnetism is still strong enough to deflect certain dangerous sun radiations, and make a compass needle move .
😲 I'm left handed! 🙂
Me too 😅
Me too
We like you anyway
Sorry for your loss
I was a lefty in my early childhood but my parents by force made me righty 😅
Here I am paying for RUclips Premium to avoid commercials and what do I get, a commercial for a lamp…
My adblocker is free.
I want that lamp which I wasn’t expext to find here, and for 15% discount! Great!
But what about the potential effects caused by the apparent periodic magnetic field reversals that occur upon left versus right selectivity?
You said that "there aren't even any pockets left in which we have a few right-handed molecules." But according to various sources I looked up, "DNA, RNA, and their building blocks are all right-handed, whereas amino acids and proteins are all left-handed."
I get that what you meant is that there are no lifeforms using left-handed DNA/RNA or right-handed amino acids/proteins -- everything on Earth uses the same chirality for each class of molecule. Just wanted to clarify that not all of those classes are right-handed.
It's still a fascinating result though. Thanks for the great video!
Now if y'all big brains can just figure out a way to make me a pair of scissors that don't laugh at me, that'd be great. Thanks
Double cut snips.
There is also the fun of ergonomic gamer mice. They keep appearing in various contexts, but are often awkward and uncomfortable to use since they are invariably designed for right-handed ergonomics...
@@BGBTech Evoluent makes the best ergonomic mice and they have left handed versions. Most products labeled gaming are kind of scammy anyways. You can almost always get what you are looking for elsewhere if you can make do without the colours or accents, especially if ergonomics is the concern since most gaming stuff is more about looks than anything else.
Most threads (mostly screws, but also things like jars, bottles, etc) are manufactured with the same handedness too, but not 100%. The right-loosey, left-tighty type are discriminated against by society. I wonder if the standard chirality of screw threads is the same as biological molecules (by chance, no doubt).
I've read that thalidomide remains in use as an important treatment for leprosy. Presumably not for pregnant patients. Though Wikipedia doesn't mention it.
I recall from Organic Chemistry many decades ago that chiral molecules were called "optical Isomers". I believe this was because they will refract plane polarized light in opposite angles from each other.
And physics is really mathematics!
Life is left handed but even Neanderthals were right handed.
Life not Just human life. But even human life is molecularly "Left handed" 🤔
Nice lectures. I am a physician by profession and love to listen your lectures on physics.
I've been having a cough last 2 days.....can you suggest something?
Asimov wrote a book called "The Left Hand of the Electron" which addressed the problem but could not provide much insight. If L-amino acid proteins arose randomly then it suggests that biogenesis may be yet another singularity--happening only once. If the chance was 50:50 and it happened often then the chance of the absence of "R-amino acid life" is vanishingly small. For 10 tries the probability is 1 in 2^10.
This is a funny choice of ad support, not bad, I’m here for you
Hi Sabine..Would you consider making a video on asymmetry in physics? Fascinating.
Years ago I read a paper that reported preferential handedness in amino acids and other molecules found in asteroids (the same handedness as for life on Earth). They searched for explanations and as far as I recall they made a link with the polarization of light coming from the sun, this light being a driver of reactions on those asteroids that produce complex organic molecules. This would be the why, if we accept the hypothesis of the origin of life being linked to preformed organic molecules raining down on Earth.
Right handedness in DNA and RNA refers to the ribose molecules selected by Nature for these polymers with Borates being shown to favour the right handed ribose isomer. Secondlly the DNA right handed spiral is created by the sum of the EM forces within the polymer . As RNA was selected initially by molecular natural selection the protoribosomes and aaRS's selected the right handed amino acids to be coded for by that RNA by a simple steric gate where orientation is crucial to the assembly process. The left handed amino acids still exist but went into metabolism and the non ribosomal peptide synthetase products.
5:00 that slight burn 🔥 actually we defaulted to wrong side as left side was due to Knights and how most of the ppl are right handed - they kept weapons in right hand -hence riding on left side of the road
I can remember there was talk about whether heterogeneous surface catalysis may also have played a role. Depending on which face is commonly exposed it may have influenced regioselectivity in favour of levorotatory molecules.
I've always thought it interesting that glucose in it's b-orientation is what comprises cellulose.
I would love to hear Sabine say “Let me show you its features!” a la The Slingshot Channel.
Having a son who is left-handed... I love sending him "left handed" stories and news! Thank you for making my day!
love your left handedness, to the least we now have a direction/rotation to become about, danke sehr
Good DNA report, quantum physics, biochemistry awesome, good study
I think there is an asymmetry in the processes the molecules are involved in. That's the most likely explanation. This would explain why we have it everywhere and not just on magnetic rocks. Don't forget, not all molecules are symmetric. If you have an asymmetric molecule, the rotation direction matters.
well, when I say the intro, my first idea was that it must be related to electromagnetism (where handedness plays a fundamental role, and this is perfectly reflected by the symmetry breaking property of Maxwell's equations).
but for me it is even more interesting to ask: why does the electromagnetic field/interaction have such handedness/chirality? or does it have? or in other words: is there a way to encode handedness to an alien without meeting them and showing them what we mean by "right" and "left"? if yes, the only way to do this is using some fundamental handedness of physics. and if we can do this, then it means that there is a fundamental symmetry breaking deep down the structure of our physical reality, right? and what would it mean if there is no way to do that?
let's look at Maxwell's equation (or to recall the right- and left-hand rules in electromagnetism). is there a way to explain the handedness (meaning of "left" and "right") to an alien solely with physical laws and terms (and using only electromagnetism)? clearly we just need to use some electromagnetic laws and systems. for example: let’s have a solenoid coil which stands vertically. if the electric current goes upwards (which means that the electrons go downwards due to our convention), the induced magnetic field also goes downwards. here I need to declare some facts:
- the expressions of “up” and “down” can be derived from physical laws like gravitation, so we can use these expressions (not like the “left” or “right”, which is the core of this whole problem).
- the notions about the direction of electric and magnetic fields are arbitrary (e.g.: in case of magnetism the magnetic field lines go from north to south, and these expressions are artificial and conventional), so we can’t use expressions like “magnetic field goes this or that direction”. in the case of the electric current we can use the direction of the moving electrons to express the direction of the current. but in case of the induced magnetic field we need something more, since we can’t directly observe the magnetic field (it’s invisible) and its directionality. that’s why we need one more electron.
inside the solenoid coil there is an approximately homogeneous magnetic field which points down according to our convention. but if we place a moving electron inside this solenoid coil, this electron will move in a circular path (orbit) due to the Lorentz’s force induced by the magnetic field. at this point we can tell our alien the followings:
“if the electrons go downwards along the coil (i.e. according to our convention the current goes upwards), then you will see the electron to move in a circular path (orbit) inside the coil. then you just need to look at this orbit from above (here we again use the logic of the “up/down” expressions). since this image is circularly symmetric, you can look at it from any direction (but it’s important to look at it from above). this is a circular motion with a defined direction, let’s call this counter-clockwise (if the electrons went upwards, it would be clockwise). if you halve this image visually (through the center of this image), then the upper half represents a motion to the “right” and the lower half represents a motion to the “left” (if the electrons went upwards, these two would be inverted). that’s all.”
so all in all we needed: one solenoid coil, electric current (moving electrons along the coil) and one single electron inside the coil. with this method we actually utilised the “up/down” expressions (derivable from gravitation) and two “right-hand rules” (one for Ampere’s law and one for Lorentz’s force).
right?
no.
in fact, it is not possible to explain the concepts of right and left to an alien with the above method either: the motion of the electrons in the coil is ambiguous since the coil has chirality, i.e. the current can flow down in two ways, and this hides the concepts of left and right.
ergo: the right and left hand rules of electric and magnetic fields are not fundamental symmetry (breaking) properties of our physical reality on their own, but together they are. and this antisymmetry is reflected by the symmetry breaking between the induction equations of the Maxwellian formalism or the antisymmetric electromagnetic tensor of the Einsteinian formalism.
Anyone else just in awe of how much complexity goes on without our ability to ever communicate to any organ in our body? But yet every organ works in perfect harmony keeping you silently alive... Just blows my mind every month or so haha.
No❤
Ehhhh not perfect harmony. Unless you're a teenager.
You talking to the right handed, they can't appreciate such things 😂
Is handedness a property of molecules in general (i.e., you can define a binary property called handedness on a "general molecule"), or is it defined differently for each pairwise-disjoint class of molecules (i.e., we arbitrarily call one orientation of thalidomide left-handed and the other right-handed, irrespective of how we assign these attributes to other classes of molecules)?
Dear Sabine, when you discuss to many science areas you should ask someone of that speciality - a biochemist in this case. He would tell you that in your body exist an enzyme who turn right-handed molecules of fructose/glucose in left-handed ones. So, there are organic molecules who pass this barrier in our organisms. Cordially your
But in thalidomide the change in chirality isn't an enzymatic or biochemical one it's
purely a chemical one probably using the energy in the body or in it's fluids to overcome a low energy barrier chirality conversion.
Always felt left handedness in humans to be due to the position of the heart in the thorax cavity, the siege of many of our earliest impulses and experiences.
The topic of laterality is super interesting, as the topic of dog food may also be of interest to many. You have enough intellect to try to know what Life is about.
I posted this on your "origin of life" video from 10 months ago: A couple recent updates have added even more agency to this topic. A "cradle lake" studied by scientists found some promising features, 1-2 feet deep, very high phosphate (phosphorus is a pre-cursor for RNA) content, very salty, lots of dolomite, magnesium, calcium, and also magnetic. The dry cycle creates a salty, jelly-like blob that sticks to the rock covered in minerals - and the magnetism (may be) the needed link to address chirality where amino acids and proteins are all "left handed" and RNA/DNA is right-handed. You can't make life without breaking that mirror image, and magnetism could be the force driving the split. Perhaps Darwin's "warm little pond" theory was spot on...
There's a video titled, "Why clever people can be stupid."
I highly recommend that Sabine and most of her audience watch it with great attention. (I'd post a link to it, but UselessTube...)