Homochirality: Why Nature Never Makes Mirror Molecules

[@SteveMould]

This one was requested by quite a few of you. I hope it answers all your questions (it definitely doesn't). The sponsor is Skillshare. The first 500 people to use this link will get 2 free months of Premium Membership: skl.sh/stevemould10

[@kirom4265]

Please make a video on voltage and current

[@Reth_Hard]

OK... But why?

[@anathaetownsend1894]

You say "sugar" and you show table sugar, like what you buy in the store, and then you say "glugose", but table sugar is most often sucrose. The chirality still applies though.

[@blindmunky]

I really like your representation of an enzymes because in a way its pretty realistic biology even molecular biology is messy.

[@martineyles]

You say it's hard to make sugar of the opposite chirality. How about making an equal mix of each chirality? After all, if it tasts more like sugar than other sweetners, doesn't have bad effects on the body, but only has half the bio-available-calories it would still be a great sweetner.

[@CellRus]

I love when physics, chemistry and biology are all intertwined and connected in your video. It brings a fresh perspective to the viewers and that all science disciplines are connected.

[@eideticex]

Chemistry and biology is physics, specific subsets of physics that are well suited to their applications. Physics is just the toolbox they are reaching into.

[@gakulon]

@@eideticex This is true but a little reductive because there's so much knowledge in these fields that you can't transfer around that it's basically useless to describe fields in this way. You can't use physics to do the work of a historian, but you can link history all the way back to physics in this same way.

[@CellRus]

@@eideticex I am well aware of this yes. As a cell biologist myself, we use various chemical and physical tools to study biology. It just fascinates me about using concepts of other disciplines that seem unrelated and apply that to biology. Of course everything is physics because we are living in a physical world, but certain concepts are really far apart that usual people wouldn't know they are actually connected, and very few videos I've seen connecting them together. So I absolutely love it when you can start bringing knowledge you know from physics and chemistry and maths and apply that to biology.

[@RalphDratman]

​@@gakulon To say chemistry or biology is physics does not imply that those fields are without content or that a standard-issue physicist would automatically know chemistry or biology. It is just pointing out that the scientific foundations of chemistry and biology, at the micro level, are within the purview of physics. Chemistry is closely bound to physics, while biology encompasses quite a bit more such as populations, mutations, behavior and so forth, which in a sense are founded in physics, but really have little or nothing to do with theories or calculations done by physicists..

[@VyvienneEaux]

I'm surprised by your comment, because I think physics, chemistry, and biology are just different perspectives on the same thing. And I think it doesn't give people enough credit to say most scientists don't know it. The overlap between physics and chemistry is almost complete. So much so that you can accurately model any chemical process using Newtonian mechanics for non-reacting conditions and quantum mechanics for chemical reactions. To oversimplify, biology is a super zoomed out view of chemistry which is a super zoomed out view of quantum mechanics. But really, there's so much overlap that there is no difference, except for the things we choose to focus on. Just one random example: a doctor reading an EKGs with telemetry. The telemetery reciever is an eye and the EKG is using exactly the same phenomenon as the heart to function. Chemistry is also deeply concerned with electromagnetic radiation and electrical potential. I'd be here all day writing a book no one wanted to read if I were to fully describe how the disciplines are all windows looking at exactly the same thing. I think that most scientists have realized this, just as you and I have. For me, I first made the realization in high school that there was overlap, but during the final semester of my biochem-chem degree when I took a quantum chemistry class called "advanced physical organic chemistry" and read portions of the proscribed Ansyln & Dougherty text (which cited mostly biological examples despite being a physical organic chemistry textbook), I realized the physics/chemistry/biology distinction is truly illusory. I think biology is more accurately "the physics and chemistry specific to life," though I will concede that life's stochastic provenance and chaotically determined outcomes have made biology less a fundamental description of phenomena and more a taxonomy of extant living processes at the macro level.

[@KhAnubis]

I‘m gonna be real with you, I‘m left handed too and I never once realized scissors could show exactly where they were cutting, I just thought you had to kind of hope for the best

[@joanapas640]

Hi

[@wilton999]

Lol. So sad. I knew that as a kid. When I came across a left handed scissors and wandered why on earth the scissors stopped working! Then, the teacher explained. I used it on my left hand and it worked. But gave up cos, I had the option, sooo...

[@someguy5766]

I'm right handed and never noticed that

[@bimbumbamdolievori]

How can you cut otherwise?.. jk

[@francisbacon4363]

I can cut with both hands, us left handed people suffer too much

[@KubuntuYou]

The real question here is, "does left handed sugar taste different from right handed sugar, and do Twix ™ bars use the correspondingly chiral sugar in their left vs right campaign?"

[@Henry-fu2hc]

These are the real questions which we need to find out

[@EMTDawg]

Yeah, if it tastes similar, your body wouldn't be able to process the wrong hand, thus possible "artificial" sweetener as long as it isn't harmful

[@russelltom2087]

@@EMTDawg this was my thought, is artificial sugar left handed and is that why it doesn't affect insulin. He just answered as I was typing.

[@RWBHere]

The real, and potentially worrisome, question is, 'What damage do molecules with the 'wrong' handedness do when entering the body?' Steve Mould gave a couple of pointers with nasal decongestants and with thalidomide. Supposing a wrong-handed form of an essential chemical was ingested, for instance, and it broke down cell membranes, or caused a cancerous mutation, instead of helping to construct cells. That would be lethal. Conspiracy theory time: Maybe an almost undetectable 'poison' form of an everyday molecule could be used to murder people. Such molecules, in the wrong hands, would open the gates for biological warfare on a mass scale. Imagine buying foods from a country which has a hidden agenda. Your FDA passes it as safe, and a large number of your population start dying of incurable diseases a few months or years later. But your medics don't know why. It might have already happened, for all we know. It will certainly have been researched. We can hope that the cost of manufacturing large enough quantities of such pathogens proves to be way too expensive for even the military of a country to consider producing them. But when a single missile or aircraft can cost many millions to produce, and few worry about the cost, our hope is unlikely to be fulfilled.

[@miinziiiiiii]

@@RWBHere delete this before a government official sees!

[@natbarmore]

It’s not just the visibility with scissors-the mechanism is designed for right hands, too. When used with the correct hand, the mechanics of our hands force the blades together (laterally) in the process of closing them, so they make a clean cut. When used with the other hand, our hand mechanics will naturally push the blades apart laterally, and with all but the very best scissors this will cause the blades to gap and not quite touch, so they’ll tear the paper or fabric or whatever, or just not cut. Depending on the scissors, you might be able to overcome this through conscious adjustment of your grip and how you squeeze them, but with many scissors, especially kids’ scissors (which tend to be less sharp and less sturdy), it’s never going to work well.

[@ere4t4t4rrrrr4]

oh my god, this explains so much things (about scissors in my hands). I never ever thought about using scissors with right hands. I thought it was just about the shape of the handler

[@EllipticGeometry]

Exactly. This has been annoying when trimming my nails. I can see what I’m doing well enough and I’m not so right-handed as to be useless cutting with the left, but the actual mechanics are horrible. It’s awkward and straining to keep the blades together. I do have higher-quality nail scissors now. If it’s still a problem, I don’t really notice because I have to compensate far less.

[@amnesite3573]

While I had half-noticed the bit about being able to see where you were cutting on onr side, I always bypassed the gapping issue by prying the blades laterally with my fingers in such a way as to force the blades together at the opposite end. Works great for worn joints. Last ditch effort was/is to ever-so-slowly draw the scissors backwards while cutting, to keep a cleaner edge in iffy scenarios.

[@ChunkyWaterisReal]

As someone who is left handed and regularly cuts suture, it's something right handed people never have to think about. Left handed surgical instrumention makes me so happy when I come across it.

[@Secret_Takodachi]

I only noticed this as a kid when I would try to use crappy "worn out" scissors with my left hand, fail to cut the paper. Swap hands & get the cut right away. The hinge that joins them flexes laterally as well as vertically, so dull scissors don't just cut worse when used with your left hand. THEY WONT CUT AT ALL lol

[@OnlyOnSindays]

1:07 made me fall of seat laughing. Imagine buying a bag of sugar and opening just to be like "Awe damn... I got the single molecule again.."

[@tatotiteta]

And then you dropped it and broke it into some glucose.

[@xostler]

@@tatotiteta damn that’s high brow

[@reallyWyrd]

Lol

[@Green24152]

Don't forget the enzyme bit.

[@SpydersByte]

yea I laughed out loud at 1:08 at the "da fu....?" :'D

[@xBris]

A small correction: 9:30 - the ribosome is not made up entirely of RNA - the "active" component of the ribosome is RNA, but the ribosome as a whole is a so called riboprotein - a complex of RNA and protein.

[@nihaal7750]

This comment ought to given more likes else Steve's mistake isnt gonna be noticed and people are gonna end up learning the wrong thing!

[@dragoncurveenthusiast]

You are both right! Pushing it up for Steve to notice...

[@davidwright7193]

However it is very important for the acceptance of the RNA world hypothesis that the formation of the peptide bond is catalysed by RNA not protein as that function has to become fixed before protein enzymes are a thing and can’t be easily replaced because it is critical for the functionality of everything else. The most likely first function of a polypeptide is to help RNA replicate.

[@Jobobn1998]

Beat me to it, xBris. As a molecular biologist, I had a brief moment of terror that I was wrong about something so fundamental before the rest of my brain came online verified that, nope, my life has not been a lie :P

[@davidwright7193]

Bosstown Dynamics no it wouldn’t. The problem isn’t biochemical it is evolutionary. Protein based ribosomes could be more efficient than the RNA based ones but they couldn’t evolve because the first enzymes to do this would be less efficient than the existing RNA based ones and would be out competed by them. Remember DNA never replaced RNA it only provides a template for RNA synthesis. The core of cellular machinery and control is RNA. DNA acts as a high fidelity, corruption resistant store of information for making RNA. Evolution has to go forwards, every step has to be more effective than the current one, evolution can’t go backwards to go forwards.

[@phs125]

Plot twist: He made the entire video to cover up the fact that he searched "meth nasal spray"...

[@halflucan]

It was err... research

[@lyokianhitchhiker]

For all you know, he searched it to make this video.

[@maggiejensen1838]

I recently googled this myself! It's Benzedrine and it used to be available over the counter and was used like a cup of coffee in the morning or for weight loss or as a cold remedy.

[@jeramiet154]

😂

[@angrymeowngi]

After watching this video, now I don't have to search for it because google is now recommending it to me.

[@RubenSteeman]

I'm left-handed and learnt to cut with right-handed scissors as well. At primary school I was really good at cutting elaborate shapes in paper because I used my good, left hand to move the paper, instead of moving the scissors to form the shapes, like most people instinctively do.

[@_loxymore_]

Hmm I need to try using my left hand to hold the scissors then

[@rigdigwus]

imagine bragging on the internet about how good you are at cutting paper

[@ernestgary6812]

Ahh... we got an expert here guys.... HEY.. GUYS EXPERT CUTTER OVER HERE!! 😅😂

[@fluffysheepfallingasleep609]

I'm right handed, but i have always moved the paper when cutting it, not the scissors

[@EricPalmer_DaddyOh]

I'm ambidextrous but use scissors with my left hand. I find it frustrating.

[@fabianglathe6131]

Dude. In my kindergarten in Germany, about 15 years ago we had left-handed and right-handed scissors

[@OneGrahamOfWrath]

Lucky. Never had access to left-handed scissors here in the US.

[@caelestigladii]

I didn't even know there are left and right handed scissors until I read your comment. Never had any difficulty using scissors with either hand.

[@BenTvHowman]

We did also in Australia. I just use right handed scissors with my left hand

[@TheCrackFox]

I grew up in the US and we had left handed scissors when I was a kid as well. I'm right handed but I prefer to use left handed scissors because I feel I have more control over whatever I'm cutting.

[@corruptedproductions5024]

Hail hi-... probably shouldn't finish that

[@NoHandleHere42]

soo many "wow" / "holy sh!t" moments from so many different science fields regarding "only" a single term: Chiral Amazing content and delivery!! Thank you!!

[@surikatga]

Get used to it. Author of this channel does it all the time.. Lately I can't get rid of very interesting topics explained in very simple way.

[@mrfranksan]

Steve is really exceptional for his multitude of talents!

[@ichbinein123]

I had no idea Ribosomes were mostly made of RNA. That in and of itself, is mind blowing, and really lends credence to how life originated.

[@sasdagreat8052]

@@surikatga I can't get enough of his style of explanations. Other people like Tom Scott have their own charismatic way of explaining random topics, but there's just a charm in Steve's videos for me.

[@shoam2103]

@@sasdagreat8052 almost everyone strives to explain things simply on KZbin. That's what's common. What's different is most other people explain quirky, mildly interesting but simple topics. Whereas Steve goes in depth to explain complex topics that we would really be curious about. He considers our perspective..

[@jeffreyv8306]

That was the best low-budget visualization of an enzyme I've ever seen!

[@elizahhoward3923]

That a hard working ass enzyme bruh

[@rianfelis3156]

I also remember something about a "shadow biosphere" where the opposite handedness does exist, but in low quantities of microscopic life. It doesn't interact much with our regular biosphere and so is very hard to study.

[@Squeph]

It's hard to study because we haven't got any proof it exists yet. It's still hypothetical.

[@Blueshirt38]

​@@Squeph But that just makes it even more enticing, doesn't it?

[@Sciencedoneright]

Well, the fact that ot doesn't interact with other things is itself an indicator for a potential shadow biosphere. We haven't seen it, so it's unlikely

[@Sciencedoneright]

For example, if you had a true left handed lion, since it wouldn't digest anything and hence wouldn't interact, there is a smal chance you vould discover it's legt handedness

[@imperturbableDreamer]

The homochirality of sugar is actually a question I asked at university and just got a shrug and "that's how it is" as an answer, which has bothered me for years. I guess the answer remains the same: it's arbitrary all the way down. But having an idea of why it is arbitrary is somehow extremely reassuring, even if I have long since moved on from those lectures. Thank you.

[@blackfootedferret]

I guess its because of the laws of physics thats the way it had to be made

[@Nevir202]

The thing I wanted to know is if you wanted to engineer something to make the ideal artificial sweetener he mentioned, would you need to go all the way down, and engineer DNA with the opposite twist?

[@ModelLights]

@@Nevir202 'would you need to go all the way down, and engineer DNA with the opposite twist?' No. First, realize DNA is not 'all the way down', it is one level up, in the other direction. Like he was saying in the video, RNA is the single strand working hardware of the cell, that makes most everything. DNA is taking the active working RNA, and adding the other side to the RNA to lock it up, so it is less active and much harder to get damaged. DNA is a security storage state, it is 'one level back up on the non-working side, for long term storage integrity of the data', not the 'lowest, working level of the genetically coded information and cellular hardware'. You would only need 'opposite sugar making hardware' to make the opposite sugar. But there's no point in making the whole opposite sugar molecule. Since it wouldn't work anyway and you don't even want the rest of 'sugar', there is no point in making much beyond 'the sweet tasting end of the sugar molecule'. You only need to make that, and basically have the rest be 'an inert holder to hold the sweet end'. Sugar stores energy. There's no point in putting the energy in to make the rest of the whole opposite sugar, you only want the small part that interacts with taste receptors, then 'something else inert to keep it all together and not provide energy'. Likely most of the artificial sweeteners are just that, 'something close to the sweet end, then a junk 'other molecule' part that doesn't really do anything'.

[@rehoboth_farm]

can you make sugar in a lab without biologically created enzymes?

[@ravinraven6913]

If someone told me that, I would have said if you don't know just say you don't know, if you answer it like that, that doesn't inspire passion. Keep things mysterious and Ill try to solve it myself.

[@ZombieLicorice]

One of factoids of the mass effect series is that life evolved on the worlds of the quarians and turians with opposite chirality. This means they have to have their own food products because the food of other species won’t provide nutrients or at worse cause really bad reactions.

[@SpydersByte]

oh wow never picked that up, ME is one of my all time favorite game series so I obviously knew about Quarians and Turians needing different foods but I didn't know it was because of chirality. I just remember them mentioning amino acids at some point.

[@Dreadtheday]

Death Strandings entire world is based on chirality.

[@adamb89]

Really it's just protein. They specifically stated that it's dextro amino acids, which means their digestive system would contain enzymes that can only break down dextro proteins into dextro amino acids, which their body could then use to build new dextro proteins. Their biology is largely similar to everyone else's, except for those dextro amino acids. So every other nutrient that isn't protein would still be levo, and perfectly digestible to them. So they probably could eat simple low or zero-protein levo foods, because carbohydrates, water, salt, etc. would still be digestible. Case in point, Turians and Quarians can drink alcohol. Ethanol iteslf is non-chiral, and can be synthesized from regular carbohydrates.

[@actuallyasriel]

@@adamb89 That's interesting in and of itself though, because alcoholic beverages aren't 100% ethanol. So you'd imagine that they'd still have issues with, for example, beer or wine, but less trouble with hard spirits like vodka. (God, I love Mass Effect.)

[@adamb89]

@@actuallyasriel True but none of those extras (tannins from natural brewing/distillation, artificial colors and flavors from whatever the hell sorority girls drink) are proteins. Maybe if you got a cordial like Rumchata or something that contained dairy, the milk protein (casein) is in fact chiral and would be something to watch out for.

[@MayaMarcello1]

I love the thought of you in the shop looking for some pasta that twists the other way

[@sp_ce.]

Just realized it’s sometimes called “dextrose” because that means “right sugar”, but that means L-glucose (left handed) should be called “sinistrose”, which just sounds evil.

[@mariusg8824]

The Word Sinister stems from ancient belief that left handedness was evil, so they called the left hand the evil hand

[@leeroyjenkins7915]

The "L" stands here for laevus, also "left" in latin. Which brings us to your proposed left-handed sugar, which would then properly called "laevulose". And guess what? Laevulose is actually the historical name for fructose, and, you can guess it, is a left-handed sugar (but is not the l-version of glucose).

[@andremarques3317]

guess i will make a villain named like that. His power is to create a gas that, when regular organic mass touchs it, molecules around the touched area reverses chirality, which would cause countless problems even if it just touch you a little. His motivation is that its hard to live in a world with opposite chirality, so his solution is to make the whole biosphere adjust to his needs

[@ArthurEKing8472]

Actually one of the chiral things that DOES exist in nature that I find hilariously interesting, is Limonene! The chemical that gives lemons their distinctive scent... Is actually the chiral mirror-image of the molecule that gives LIMES their unique scent! And we can detect the difference between the two!

[@GameShaft]

Terp

[@shawn5809]

Its actually between lemons and oranges, not lemons and limes

[@sieltan5618]

I think d limonene is found in citrus peels and l limonene in mint oils, actually

[@brusicor02]

It’s not : limes, orange and lemons contain the same enantiomer : (R)-limonene. (S)-limonene can be found in plants, like mint and eucalyptus. And for the odor difference between the two... it’s not obvious, most of commercials samples contains impurities and can affect the final odor. Citation from Mans H. Boelens, Harrie Boelens and Leo J. van Gemert, "Sensory Properties of Optical Isomers", Perfumer&Flavorist, Nov. 1993 : « Very pure (R)-(+)- and (S)-(-) -limonene both have a harsh, terpene-like odor, however the (R)-(+)-enantiomer has a fresh, slightly citrusy note and the (S)-(-)-enantiomer a turpentine-like note. Randebrock investigated the threshold values in air of the enantiomers of limonene [...]. No significant difference was found between the two enantiomers. »

[@kennethbransford820]

@@brusicor02 This too is also by design. Evolution = Self Assembling Atoms =Impossible

[@Cliff86]

In some mirror universe, Matt Parker replaces the head of Steve Mould in a picture with Captain Kirk

[@rebmcr]

No, the video clearly states that in the mirror universe, Matt dies from malnourishment.

[@pitri_hub]

@@rebmcr Not if it's also mirror matt. The malnourishment only happens if your and the universe's chirality doesn't match up.

[@rebmcr]

@@pitri_hub Parker Glucose

[@SamTahbou]

Fun conclusion to a movie where the mc ends up in a parallel universe, starves in short order.

[@josephburchanowski4636]

​@@SamTahbou How about a movie where you meet a 4-dimensional being, and when they return you to your world, they accidentally had you flipped the wrong direction. Kind of how if 2-dimension beings exist, we could accidentally flip them and change their handedness. . When you return, you realize everything is flipped from left to right from how you remember, and you panic realizing what has happened and that you are going to starve unless something is done.

[@VikasSBhat]

“Grand cutter of things!” Beautiful.

[@Gamma_Digamma]

CRISPR CAS9 reference I think

[@TrainString]

Get on with it

[@mrfranksan]

See SmarterEveryDay’s video on riding an inverse steering bicycle. He spends eight months training his coordination to ride a mirror steering bike. Steve could train himself on left-handed scissors with great effort.

[@Friend_of_the_One-Eyed_Ladies]

Aviation snips (tin snips) come in 3 main flavors: left cut, right cut, and straight cut. Red, green, and yellow handles, in that order. You need all 3 types to do tin work. The left and right are mirror images of each other. The reason you need both left and right cut is so you can cut left or right curves. You can't cut a counterclockwise ("left") circle/curve with a right-cut snips, and vice versa. Right-handed people typically use the left-cut (red) snips most, but both left and right snips are in constant use.

[@solarsynapse]

My awesome U.S. made Midwest 90 degree red handle snips are marked "right" for right-handed use to cut left. They also cut fine for straight.

[@Secret_Takodachi]

Being a lefty means you've either "always got fresh tin snips you can use" or "you gotta make do with the beat-up righties" Goddamn feast or famine with everything in life as a lefty. A little consistency sure would be nice lol

[@NoNameAtAll2]

what stops you from flipping it over? don't you cut flat sheets that are flip-symmetrical?

[@trequor]

​@@NoNameAtAll2Messes with the cut. Metal is rigid and cutting it permanently bends the metal around the cut. You want to curve the metal the right way and leave a proper edge on your finished piece

[@Wanhope2]

Straight cut mains unite! (For everything, with meh results!)

[@chrisbovington9607]

Typical Steve Mould video: Here's a small detail I noticed about sugar. Yeah, but how did life begin?

[@Deddily]

Fun fact: dinner knives are chiral. If you think I'm joking, go and check one - the serrated edge is on the outside for a right-handed user, which helps in cutting together with a natural pushing-out motion which happens when using it in conjunction with a fork.

[@BarbarianGod]

They seem to be on the left side if you're holding it in your right hand over here in Slovenia for whatever reason

[@andymcl92]

I'm left handed, but I use a knife and fork the "normal" way. To be honest, I think that's better. Right handed people using just a fork use it in their right hand, but when using both, they guide food to their mouth with their non-dominant hand! Meanwhile, I (and a lot of other lefties) always have the fork in my left hand. The thing that switches is a knife. K&F, the knife is doing rough cutting/sawing so doesn't need precision. Chopping veg or buttering something, the knife is in my left hand for more delicate work. Makes sense to me!

[@Deddily]

@@andymcl92 I eat the "wrong" way - knife in my left hand, and I have always struggled to cut things like meat. When I discovered that knives are right-handed, everything suddenly made sense

[@matthewm3]

Go to anythinglefthanded. co .uk they have a video about left handed things they offer including knives. (It’s the website he said in the video)

[@davidioanhedges]

Steak knives are chiral, knives in general are not .. Swords can be chiral as well

[@TonyTigerTonyTiger]

0:45 No, in biology, "right handed" doesn't deal with the direction of rotation of light, it has to do with the bonding arrangement of the atoms in a molecule, such as those bonded to an asymmetrical carbon atom. Some right handed molecules rotate light to the left, and vice versa. For example, as a rule all the chiral amino acids in biology are left handed, or L-amino acids; but many of them rotate light to the right. "Of course, the L and D designation of an amino acid does not indicate its ability to rotate the plane of polarized light. Many L-amino acids are dextrorotary." Fundamentals of Biochemistry: Life at the Molecular Level: Fourth Edition, Donald Voet, Judith Voet, and Charlotte Pratt, John Wiley & Sons, 2013 , p86

[@Shrooblord]

Thanks! And with a reference, too. Good stuff

[@lostspace5811]

Just referring to amino acids doe?

[@Virtuous_Rogue]

@@lostspace5811 If I'm recalling correctly, the D and L for a group of molecules is based on the reference molecule. So probably glucose monomers rotate light to the right and then all sugar monomers produced biologically are just declared D-____ose. Alanine or Glycine would make the most sense as a reference amino acid and one of them rotates light to the left so now all amino acids of biological origin are L.

[@lostspace5811]

@@Virtuous_Rogue is that an accurate generalization they make or is it absolutist and lazy for teaching purposes?

[@Virtuous_Rogue]

​@@lostspace5811 I pulled out the Voet and Voet book to review this because I wanted to be certain about what I said. Turns out the D-L system (the Fischer convention) has a single reference molecule, glyceraldehyde. Amino acids and monosaccharides are called D or L based on reacting the chiral center carbon into glyceraldehyde one group at a time and at the end, seeing what form of glyceraldehyde you have. The chiral center of interest on an amino acid is the same for all of them so D and L are useful for comparing which amino acid form you have based on which direction the R-group is pointing relative to the other three groups. So D and L are descriptors of structure rather than optical activity of amino acids. Sugars are more complex because there are multiple chiral carbons and multiple chain lengths. Because all monosaccharides have a carbonyl group (the carbonyl group is required to switch between linear and cyclic forms), the chiral center of interest is defined as the chiral carbon farthest away from the carbonyl group in the monosaccharide. Differences in other chiral carbons get defined with completely different monosaccharide names. Generally, the D form of monosaccharides are seen in biology but Voet and Voet note that some L-form monosaccharides do show up. Source: Biochemistry, 4th Ed. Voet and Voet, pages 73-78 and 359-363. If you want a more detailed description, google Voet and Voet biochemistry PDF and it should be pretty easy to find. I also find wikipedia to be pretty accurate and clear when it comes to science and math pages.

[@ennothedishonorable5530]

Just noticed, wouldn't that also mean, that ones immune system would fail in a mirror dimensions since every bacteria and viri would be incompatible to our antibodies?

[@samidans6815]

we would also be incompatible for them so we won't get sick in the first place, we have nothing they can use

[@ennothedishonorable5530]

@@samidans6815 Let's hope so. Imagine someone comming from a mirror world, bringing mirrored COVID and we have to give everyone mirrored vaccines again.

[@captainsmolletkermit8986]

@chu Harry but they're extremely specific in what they bind to

[@eralp.celebi]

@@captainsmolletkermit8986 damn I didn't know that

[@ravinraven6913]

the proteins wouldn't be able to fit so I don't think you could get a virus

[@KurtCollier]

fun story- this video is how I learned that when we go looking for life on other planets we bring sweets, and even make an effort to get the type you might like.

[@EQRuges]

Come here little alien, want some candy?

[@abrasmage]

@@EQRuges Now get in the alien van!

[@Shrooblord]

Awwww >w

[@Mr_Mooo]

This has been the most interesting youtube video that I have seen on youtube in a long time. You are a great explainer with a great dry sense of humour.

[@echoybyte42]

Lol "trogdor". Forgot about that haha

[@hexzyle]

He was referrencing Richard Feynman's breakdown of the question "why"

[@_Leouch]

There are multiple good quality channels like this one. just sayin :p

[@billbaggins]

Steve may be absent for a while as the IAEA investigates his unauthorised knowledge of so many nuclear bases.😁

[@kristyanne719]

Good one!

[@pizzataster]

*Nucleotides ffs

[@robnorris4770]

Use Skillshare, go to jail.

[@BlastingAgents]

9:29 just to clarify: The ribosome consists of both, proteins and RNA, whereby the catalytic site is made from RNA; so, strictly speaking, it’s not only tangled-up RNA.

[@davidf2244]

I enjoyed the guy in the background's "get on with it!"

[@raymondwhatley9954]

Kind of surprised I didn't see any comments about the Mass Effect Trilogy. The Turians and Quarians are stated to have the opposite chirality relative to humans and can't eat our food because of it. There's even a nice little bit you can overhear in one of the games where a guy is trying to buy both kinds of spices in order to give his food more of a pop and the merchant says "You don't want to mix chirality with your spices".

[@vblaas246]

That is cool, didn't know. I missed that game and now it looks kinda old and don't really have the time.

[@mikecrapse5285]

@@vblaas246 it has some remaster

[@XDarkGreyX]

​@@vblaas246 "looks kinda old" .....

[@theneoreformationist]

You're kind of old

[@Wanhope2]

Also in the book/show series The Expanse!

[@TallinuTV]

Awesome in depth explanation. That Mars sugar experiment, I realized they probably sent two containers with the left and right handed sugars separated, so they could tell if one of them was being depleted at a different rate than the other, to distinguish between forms of decomposition that would affect both equally and therefore not indicate presence of life.

[@nati0598]

I think that separating them would be pointless, it's much easier to tell the chirality of the compound after part of it is consumed than separating it in the first place.

[@michaeldubery3593]

My primary school in the UK had left-handed scissors available for all classes. They were identifiable from the 'normal' scissors as they had one yellow and one green plastic handle on each pair, where the RH ones were all red or all blue.

[@MichaelClark-uw7ex]

Ours had them in the USA too but just like the left handed desks, the right handed aholes took them because they thought it was cool and a bit of bullying.

[@Bayonet1809]

Mine in New Zealand had them too, but while the school had the correct total number, they had the wrong ratio for my class, and I was always slow at grabbing them, which meant that I had to use left handed scissors despite being right handed.

[@askthisscientician6040]

How to irritate a biologist: just say "RNA is the single strand version of DNA"

[@CaveyMoth]

URGH! What about Uracil?!

[@wierdalien1]

@@CaveyMoth WHAT ABOUT THAT HONKING GREAT SECOND OXYGEN?!

[@Porkey_Minch]

I've never heard of what makes them different, so as far as I know it's true.

[@wierdalien1]

@@Porkey_Minch RNA has a second Oxygen, hence why DNA is DEOXYribonucleic acid

[@Porkey_Minch]

​@@wierdalien1 I see, thank you.

[@FalcoGer]

left handed screws are used quite a lot in machinery that turns, such as motor drills, because you don't want the machine to loosen it's own screws.

[@TtttTt-ub5xb]

Yeah that's right

[@steveunderhill5935]

Propane and propane accessories- Hank hill

[@Quon]

imagine having screws and screwing on another machine, they're kinda doing surgery

[@matthewsiebert816]

A couple things: 1) molecules in your title card/video image are not enantiomers, 2) re 3:16 there are plenty of molecules produced in nature that are enantiomers, albeit not necessarily in the same organism. One example: spearmint oil (smells like spearmint) and caraway oil (smells like caraway, and is the characteristic scent in rye bread). They are enantiomers of one another and processed by our olfactory sensors as different scents/flavors.

[@ericrawson2909]

Thanks, saved me writing., The thumbnail reflection is not a mirror image!

[@TheInternetEnzyme]

This is probably one of the most intriguing and inspiring videos on KZbin

[@tjejojyj]

I love the peeling of Feynman’s onion. We got to the “we don’t know” layer later than I was expecting as there was a lot to absorb at each stage. Well done.

[@Sicarius1024]

2:43 Not entirely true. You have stuff like carvone where L-carvone gives spearmint its flavour and D-carvone gives caraway its flavour. Two enantiomeres that exist in nature, though admittedly not in the same organism. 5:55 Arthur C. Clarke explored the concept of someone going through a space anomaly and being mirrored in the story "Technical Error"

[@PhilBoswell]

As I learned from QI, limonene is likewise different depending upon chirality: en.wikipedia.org/wiki/Limonene

[@JimC]

A similar duplicate of Spock was created in the first Star Trek novel, "Spock Must Die!" by James Blish. The duplicate barricaded himself in sick bay so he had the time and resources to make food with mirror-image molecules.

[@transkryption]

and there are fingi that make prions according to Wikipedia.

[@Skaos87]

Thank you for the Arthur comment. Cost me a good 6 hours of my life. For a good reason!

[@tesmith47]

@@transkryption damn

[@AgeingBoyPsychic]

I'm starting to think Matt Parker might be in danger...

[@davidbergmann8948]

Who? 🍄

[@PopeGoliath]

@@davidbergmann8948 That Square guy, I think. 🌚

[@alexandreboth1001]

@@PopeGoliath Isn't that Steve from Minecraft?

[@yashvangala]

@@PopeGoliath the Parker Square guy?

[@PopeGoliath]

@@yashvangala that's the one.

[@xavierjust8681]

Really nice video. However, both L- and D-limonene are naturally occurring. Fun fact, because of genetic reasons, some people can tell them appart, others don't.

[@seponkiuas]

Exactly, some bacteria can also produce both L-lactate and D-lactate

[@devforfun5618]

how can people tell them apart ? by taste or color edit: saw in another comment, it is smell

[@xavierjust8681]

@@devforfun5618 don't know about smell, but some can tell them apart by taste. We did actually test it in class.

[@SwordOfApollo]

Also carvone. (-)-carvone is the main smell of spearmint, (+)-carvone is the main smell of caraway.

[@SmokeandLights]

I've been thinking about this video a bit lately, in relation to a 4th dimension phenomenon. I saw a video that explained that a 4th dimensional being would be able to "flip" a 3 dimensional object, much like we can turn a piece of paper, leaving the object mirrored. Sadly, I cannot remember what it was called or what channel it was on. The implications of that are pretty significant to life , if you take into account the concepts covered in this video. A 4th dimensional being could flip you over, and pretty much make you die very quickly, if your molecules were incompatible with the ones you need to survive.

[@vblaas246]

A 4th dimensional being could have a 4th dimensional mirror image, that is more impressive imho. Also thinking about Matt Parkers hypercube unfoldings recently.

[@ColonelFredPuntridge]

Probably something based on the novel *Flatland* by *Edwin Abbott* or maybe the sequel (by a different author) which is called *Sphereland.*

[@cheeseburgermonkey7104]

CodeParade's 4D Golf devlogs, perhaps?

[@malcanth3481]

That is absolutely horrifying to think about. When you flip a piece of paper, you are essentially swapping the sides along a single axis. Imagine having this done to your body in the 4th dimension. You feel a firm shove on your back, and your body is shoved through itself. You are facing the opposite direction. You look the same, but your body was mirrored. You struggle to see as your brain tries to comprehend having your eyeballs swap places. You look to the left, but your eyes move right. You look to the right, but your eyes move left. Your head is starting to hurt. You raise your right hand to grab your head, but the arm on the left side of your body moves instead. You know for sure that you are controlling your right arm, but the one on the left is moving. Now you are getting dizzy. Nothing is making sense. All you felt was a shove, and now your body isn't working. You start to fall over and reach out to catch yourself, but the wrong arm moves again, so you fall face first into the floor. The left side of your face smacks the floor, but you feel the pain on the right side of your face. How does this make sense? The side of your face that hit the ground feels fine, but the unharmed side is what feels the pain? The 4th dimension is terrifying. And a 4th dimensional being would probably be equally terrified of a 5th dimensional being. Just adding access to a single extra spacial dimension would truly give one the power of a god.

[@qualia765]

This is how _all_ education should be, ask a question, answer it but have another question and answer it and repeat it until you have answered everything. School kinda already does this, but not enough. Keep making great videos Steve! I learn more for you than 'most anywhere else.

[@vacronda]

This is one of the most interesting videos I've seen on your channel but also anywhere. The concept of chirality is completely mind-blowing! Thanks for sharing it with us/me.

[@ks220]

this was one of the most mind blowing videos I‘ve ever seen. I‘m so sorry for all the people at parties who will have to listen to me rambling on about left handed sugar

[@richardlilley6274]

Love the cgi.. Cloth generated imagery. Priceless.. Great explanation from what we can comprehend with out left/right handed brains

[@celineguler]

i love how you ask the question for us and answer it because the teachers be like T:...so plants always make right sugar. Me: wait but wh... T:yeah sorry no questions we out of time

[@Lebenspiel]

It's kinda sad when the internet gives you more answers than the whole education system.

[@holyroyaler8592]

​@@Lebenspiel That's what you should expect to happen when the government is in control of something.

[@ZunderCraft]

@@holyroyaler8592 totally agree, they are also writing their own version of history. Cool world we live in

[@gunblad3]

And all this within 20minutes. But of course he took weeks/months to prepare properly for this video we see

[@jasonpatterson8091]

Sorry you have poor teachers.

[@Parmigiano1]

L-Glucose, the perfect sweetener, is around 100 USD/g.

[@YourMJK]

Once someone creates a genetically modified left handed plant we'll be one step closer to Utopia. Looking at Americans, I think we desperately need more research in this area.

[@Parmigiano1]

@@tbird-z1rIt's possible. Some molecules can have the same effect, some different. For example D‑penicillamine is used as a drug, but L‑penicillamine is toxic. Some can have different smell/taste e.g. L-aspartame is used as a sweetener, but D-aspartame is tasteless.

[@vlogerhood]

We already have the perfect sweetener. R-Glucose.

[@vlogerhood]

@@YourMJK You only think that because you don't know what you are talking about and believe false nutritional propaganda.

[@YourMJK]

vlogerhood "Nutritional propaganda"?

[@anthonylloydii96]

The video that precedes this made me remember my organic chemistry classes from undergrad, but I was upset you never used the word "chiral" or talked about why sugar (and other molecules) made in nature have particular handedness preferences. This video is a great follow up to that one, though! Thanks for making this one!

[@billmcdonald4335]

Arthur C. Clarke wrote a short story back in 1950 called 'The Reversed Man' later re-titled to 'Technical Error' in which this very phenomenon was a crucial part of the plot.

[@Minihood31770]

The "why this chirality" question reminds me of the "why matter and not antimatter" question from cosmology. One can imagine 3 mirror universes, identical in every way, but with opposite matter, opposite chirality, or both!

[@carultch]

4 mirror universes. 1 with matter and left-handed chirality 1 with antimatter and left-handed chirality 1 with matter and right-handed chirality 1 with antimatter and right-handed chirality

[@Oturan20]

Although if we were in a Universe Made of Antimatter we would call that Matter, and the other Antimatter.

[@solitare4602]

@@carultch OP is assuming Our World and 3 Mirror Universes. That would be 4 worlds total.

[@TheOmegaXicor]

All four asking why this way and not the other

[@steveunderhill5935]

If all visible universe had once been shot out of one of the pole astrophysical jet of a spinning super massive black hole, would all matter on one pole not be homochiral? (Evidence being visible universe has a LH preference)

[@justpaulo]

Shaking hands?!? Oh, that's so much 2019!

[@alexnoman1498]

"so very" fits better, here

[@leomadero562]

Just "so" is better here

[@LeonaPrime]

The hands knew what was next; they were afraid.

[@pedrexsevenz1856]

Wusses over a fake staged plandemic.

[@kaaiplayspiano7200]

@@pedrexsevenz1856 can you like not ok thanks bye

[@kilroy987]

Limonene + and - have the same molecular makeup, but the atom groups are arranged differently in the structure, generating either a lemon smell or an orange smell. Fascinating. The receptors in the nose are partly designed to respond to left or right handed molecules, so they smell differently.

[@jasonpatterson8091]

Minor clarification: A particular biological pathway produces only one enantiomer (left or right), but it IS possible for different biological pathways to produce each enantiomer separately. A good example is carvone, the molecule responsible for the flavors of caraway (R-(-)-carvone) and spearmint (S-(+)-carvone). Each plant produces one version of the molecule, but both versions are able to be made.

[@jpdemer5]

@Martijn van Steenbergen Our odor detectors are proteins, which are chiral molecules, and therefore they (and we) can distinguish between the enantiomers of most chiral molecules.

[@Philipeace]

Imagine having to make an entire 18 minute video because you accidentally googled "meth nasal spray" and realised fbi gonna fuck u up

[@Steppenkater]

When I was 25 I switched to a left handed mouse. I always used my left hand for the mouse but I used my middle finger for the main button. It took me no time to get used to the index finger shortly after using the left handed mouse because it has the buttons mirrored. Another example where I use a left hand tool is a caliper. I use the scissor with both hands. Left hand for fast effortless cuts, right hand for slow precision cuts.

[@LaserFur]

I switched mouse hands as well since my wrist started bothering me. I still use the pointing finger for every button though and I don't tell the OS to swap the buttons.

[@mal2ksc]

I have a mouse on each side. The one on the left, I opened up and physically re-wired to swap the buttons. When I had to make a service call on basically no notice, I grabbed the first mouse I could find on the way out the door, and it was the re-wired one. That was kind of annoying.

[@cesarjoughin]

Finding out about these sort of things makes the fact of life so much more amazing, and also how time travel and space travel is way harder

[@ottodude555]

"Get'on wi it!" busted a gut lmao

[@kantpredict]

Bit of Monty Python there 👏

[@Derpy1969]

kzbin.info/www/bejne/qYmoaX-ajd-Yfq8

[@Macieks300]

This might be the most interesting video about chirality I've seen on KZbin.

[@MilesEques]

the photograph scissors subplot ought to be deeply unsettling, but Patrick Stewart has just such a lovable face that I can't help feel satisfied by the ending.

[@HoraceMash]

Genius communication! Thank you for all your wonderful work Steve. You are doing the world a great service!

[@TashiRogo]

1:07 I laughed way too long at this bit. What a great edit.

[@kookeekwisp]

10:08 I love the "ffs" there. Steve mould is my spirit animal

[@Mojoojo95]

“Get on with it” I need one of those people in my life

[@kelvinliu-huang5955]

2:06 underrated enzyme visualization. Why isn't this used everywhere??

[@bartonstano9327]

Love the enzyme model [a piece of blue cloth] ; it is some respects a good way to explain to people with lots of biochemistry background

[@Pedro-re2pv]

I'm not studying science or anything similar. I just find this extremely interesting, and you make it even more interesting. Great work! Please keep it up if you have the time.

[@joshuasmithd21]

I'm left handed as well, and for years of my life I never knew the full advantage of left handed scissors; not only can you see the cut, but the gripping motion of your hand pulls the blades together giving a better cut! My ergonomics teacher in college taught me that. And I never realized when I was using right handed scissors with my left hand I was making extra effort to pull the blades together with an awkward movement. And I thought it was just the handles that were uncomfortable =/

[@TerenceA72]

My son is left-handed, when he was child I went to the Early Learning Center (mostly educational store in the UK, no idea where you're from obvs) to buy left-handed sissors, I hand a crazy argument with the staff as they all refused to believe that left-handed sissors existed, wound me up to be honest lol.

[@terrysullivan1992]

Years ago I saw a video on left handed sugar and what a revolution it would be in the food/diet industry. Been wondering why it hadn't come to market. That is why I watched your video and it was very interesting. If the cost of making left handed sugar could be brought down to commercial viability; your explanations of the very different, and sometimes very harmful, effects of mirror molecules would still need lots of testing. I remember the Thalidomide debacle decades ago.

[@imnotlettingyouseemyname]

They also did a study and found that when giving 24 grams of left-glucose for colonoscopy prep, 80% of colons were rated as excellent or good. A can of soda has 39g of HFCS, which is 1.5x sweeter than glucose. The good news is that preparing for a colonoscopy would be much easier.

[@Kanbei11]

You also have to make sure that the body doesn't change one enantiomer to the other in Vivo. See your example about thalidomide

[@omarb2653]

This is the basic concept of calorie free sweeteners: make something shaped enough like fructose or sucrose to bind to your taste buds and taste sweet, but also design it so that your body cannot metabolize it was energy. That’s what Splenda and aspartame essentially do

[@rehoboth_farm]

can you make sugar in a lab without biologically created enzymes?

[@omarb2653]

@@rehoboth_farm Absolutely you can. There are plenty of reactions that are stereoselective (selective for left or right handed). However, generally speaking sugar synthesis can be difficult because there are many identical or near-identical locations on a sugar molecule. This makes it difficult to preferentially modify one location over the other. So yields might be low unless you can figure out a reliable synthetic route to make the sugar you want that has high yielding reactions. There are some workarounds for this, like using fancy protecting groups to block certain locations you do NOT want to react with until you are done, then you can deprotect those locations. Hope that makes sense, lmk if you have any other questions.

[@amk1108]

This man delivers content really well. Calling this content is frankly an insult...its more like a masterpiece!

[@davidbonar5190]

you seem very... content :D

[@vaszgul736]

so you are telling me we brought candy to mars to see if the martians would come out

[@KILLRXNOEVIRUS]

👁👄👁 b r u h

[@divyangana123]

😂😂😂😂😂😂

[@pyrogue3785]

Remember martins never accept candy from a white lan(der)

[@dexio85]

3:45 You should have used Parker's Scissors here...

[@prajwolshrestha5573]

Just flipping the scissors can do the job, I use my right hand more though

[@derradfahrer5029]

I had to laugh so hard, watching Steve cut off Matts head.

[@Nate9273]

Friendship ended with Parker...

[@dexio85]

@@Nate9273 How so? A KZbin drama ? :D

[@Nate9273]

@@dexio85 don't you see his photo? Now Jean-Luc is his new best friend...

[@benzenering2183]

Great video! I think the concept of homochirality was explained very well. However, there are a few mistakes that I would like to address. 1) If we tried to make sugars in the lab (or other chiral molecules), we would not always end up making a 50/50 mixture of enantiomers. This might have been an intended simplification, but I think it is good to mention the truth for clarity. A lot of reactions do indeed produce a 50/50 mixture of enantiomers, but there are many examples of reactions where a 100% pure enantiomer is made. There are also some ways to bias the enantioselectivity of the reaction one way or the other, but it's too complicated to describe in a comment. Also, what's actually more common in organic chemistry is to be concerned with the changes in the chirality of individual stereocentres found in a single molecule. A stereocentre is essentially a carbon atom that has its own handedness, and a single molecule can have multiple of these 'handedness' centres. If two molecules have most of their stereocentres being identical, but some of these stereocentres differ, these molecules are referred to as diastereoisomers. It's actually a lot more common that reactions only change the stereochemistry of one or a couple of stereocentres in a molecule rather than all of them at once. In some reactions, we end up making a 50/50 mixture of diastereoisomers, while in some cases we make 100% of a single diastereoisomer (so-called stereospecific reactions). There are also other cases where we selectively make a biased ratio of stereoisomers - something like a 90:10 mixture (so-called stereoselective reactions). 2) Not all DNA is right-handed. Of course, this might have also been intended, but I think it is good to mention that in some rare cases we could have left-handed DNA, and that can actually happen in living systems. This is a pretty good article, if anyone is interested: www.the-scientist.com/features/left-handed-dna-has-a-biological-role-within-a-dynamic-genetic-code-67558. 3) In chemistry, there are also some pretty ingenious ways to purify mixtures of enantiomers that do not involve the complex use of enzymes or anything like that. For that, we could use the properties of stereoisomers that I have mentioned earlier - diastereoisomers. While enantiomers have identical chemical and physical properties, most diastereoisomers actually have different properties, such as their boiling point or solubility in various solvents. If we take a mixture of enantiomers and react it with a different molecule that is 100% enantiomerically pure, we would get a mixture of diastereoisomers corresponding to our starting materials. We could then take that mixture of diastereoisomers, purify it using their unique properties, and get 100% (or nearly 100%) pure diastereoisomer. By using a reverse reaction of what we did at the start, we could then turn that diastereoisomer back into the starting material, giving a 100% (or nearly 100%) pure enantiomer.

[@DrReginaldFinleySr]

Amazing video. I'm glad I bumped into it. You have given me some additional examples of chirality to share with my students. Much appreciated.

[@vblaas246]

Don't forget about "Righty tighty, lefty loosey" and bring a screw and some wood. Then make them forget about the confusing 'right-hand rule'.

[@Pepso8P]

"Nucleotides ffs." :D This was very well made, I always hate it when an answer raises another question which isn't answered afterward. And you just kept on going, answering all the emerging questions!

[@nubnubbud]

you just keep going... till you run out of cake?

[@user-wq1dt7li2x]

So, what I'm hearing is; that plot nonentity "dextro species can't eat levo food" from Mass Effect actually had some legitimacy to it. Neat

[@henrypaleveda7760]

I was thinking of having things like that in my scyfi universe (a bunch of inter-related stories)

[@cynthiafer3850]

@@henrypaleveda7760 47riri8

[@cynthiafer3850]

@@henrypaleveda7760 .nny

[@toasty9531]

1:09 You don’t buy glucose from the stores. That’s sucrose which is a disaccharide containing glucose but also has a fructose attached to it. This doesn’t matter too much with this example because both are chiral.

[@tatsuyashiba6931]

Another dificulty with scissors is that since theyre designed for right-handed use, the forces needed to cut are oriented for that hand. As a left-handed myself, i need to "press" the sides of the scissors in a certain way thay would mimic the forces applied by a right hand, otherwise it wobt cut properly. Doesnt happen if the scissors are tight, but becomes noticeable when the rivet loosens

[@Soandnb]

3:55 This sounds like the tragic backstory of a mad scientist.

[@johnbeauchamp1743]

I was fascinated by this question in my undergrad. I came upon a paper whereby it was suggested that primordial organic compounds were first catalyzed or influenced by circularly polarized light radiation from a pulsar or other cosmic event. Thus resulting in a homochiral bias that could more easily polymerize and evolved into life itself. So cool!

[@stephenconnolly1830]

Yes, but the effect is miniscule - over a long time period, of course, it would be more significant.

[@Ricval33]

That sounds really interesting, any chance you have that paper?

[@pjrenegades5661]

Probably not a popular position, but the more I learn about biology, specifically DNA, the more inclined I am to see it as a "divine fingerprint" if you will. The odds of life are absolutely ridiculous to even comprehend. Since it sounds like you are well educated on this subject, what is your opinion on the matter for the being a "creator." I'm not well educated and never went to college, and would really like to hear your thoughts.

[@beanboy5315]

My organic chem classes failed me so much. We had this immigrant professor that had such a thick accent and such poor grasp of the language she could never even hope to explain these concepts in a meaningful way. She knew her stuff but couldn't put it to English words well. This made more sense than I could ever get out of my university course. Thanks

[@rehoboth_farm]

can you make sugar in a lab without biologically created enzymes?

[@louisstuyck5866]

4:00 Thats so sad, I've used left-handed scissors since I was five and it's way easier to use as a lefty.

[@jjtt]

I have the exact same problem as Steve, I cut with my right hand even though I'm not right-handed

[@benjaminshropshire2900]

I tend to cut left handed, (but sometimes right). Regardless, I always use right handed scissors. I've learned to hold them differently depending on which hand I'm using to make them work correctly. (BTW: it's not being able to see that's dictates which way they are built, it's that that the natural way to hold them pushes the blades together, or apart, depending on which way they are built.)

[@ShirinRose]

I had a small pair of left-handed scissors when I was in primary school, but since right-handed scissors are so prevalent I had to learn how to use those too, so now I don't notice any difference in ease of using left- or right-handed scissors. Annoyingly, I only learnt to use a computer mouse with my right hand, to the point where I now still find it easier to use the touchpad on my laptop with my right hand 🤦‍♀️

[@goosekick4]

After I learned about chirality in grad school I understood that Alice upon entering the world in the mirror would have eventually died of starvation

[@SmokeandLights]

Amazing video. I've never heard about molecular handedness before now, and you explain it very well! I am kind of proud that I found myself asking "but what about right handed sugar as an artificial sweetner?" before you brought it up near the end.

[@rosebrigade]

3:17 The sad part is, reverse-thread screws and bolts do exist, and it actually is annoying when you actually find them by accident. Luckily they do usually label them as reverse-thread or something similar, but sometimes they don't, and it's annoying.

[@QuantumLeclerc]

I work in mechanical engineering and left-handed threads are surprisingly common, especially for applications where a component spins clockwise and you don't want it to unscrew itself or loosen from vibration. The issue we have is when we can't find a tap that's right hand...

[@alexanderbrady5486]

I am left-handed with a left-handed parent, so I actually DID have a pair of left-handed scissors growing up. I can tell you it was terrible! Sure, I got to use the nice left-handed scissors at home, but how often do you take scissors with you? Because I ended up borrowing scissors, as most people do, I also learned to use right-handed scissors, but I grew up knowing how much easier left-handed scissors are for me to use so I knew just how much worse it was the whole time.

[@SheepUndefined]

I was literally always treated like a dumbass for preferring not to use scissors over stuff like Xacto blades in high school at class. It felt like I was just horrifically bad at cutting, that it was somehow a skill only I didn't have, and that the only difference between using it leftie was that my fingers got stuck more easily in the handles. Never knew that you were supposed to be able to see the blade intersection and not just guess, dangit.

[@rizmi73]

Hi Steve, this is the best video I ever watched in the entire KZbin, ever. We all learn about chiral molecules in chemistry, never think this far. Amazing.

[@Steve-kj9tx]

Walter White taught me everything I need to know about chirality

[@stevenmiklasinski3705]

How do you decide if something is left-handed or right-handed? i get the idea that one molecule looks like the mirror image of another one, but which one of those is right or left?

[@DankDungeon]

They make it up

[@theodorthorsen8047]

the reason it isnt symmetrical is because the molecules have different spacious structures. this happens because one of the carbon atoms have 4 different molecules/atoms bonded to the carbon. that way it can’t be mirrored. the different molecules/atoms have different chemical priorities when it comes to naming them. You give 3 of the molecules\atoms a number based on how their prioritized. 1 for the lowest prioritized and so on. if the numbers rise when you count them clockwise, it’s a R form. Counterclockwise it’s a S form. so it’s based on which way the asymmetrical carbons bindings are prioritized and how you count them

[@michaelhart7569]

Steven, it is really just a matter of definition. In the past, molecules such as sugars and amino acids were simply named after which way they caused polarised light to turn, left or right. Over time chemical nomenclature developed to describe chiral molecules based on specific chemical structural rules.

[@ВасилийБлаженов-ж9е]

Yeah, probably the greatest and also the most boring achievement of IUPAC is the nomenclature that can be used for EVERY organic compound, aleven those that aren't discovered yet. A system to name more than 30 millions compounds, and the rules can fit into a couple of pages...

[@mrgreatbigmoose]

It depends on it being called D- and L- or R- and S-. R- and S- are based off of alphabetical rules. Well, no that's a bit of an oversimplification but it's a system of rules based on assigning priorities, where you start counting and in which direction you go - clockwise or not.

[@Т1000-м1и]

I literally learned more biology then in school from a video not about biology

[@samma676]

This extends the end of one of those goosebumps stories that actually haunted me for a long time. When the kid got tricked into swapping with his mirror image, and his mirror image got to live in the real world. That dude died. Couldn't digest a thing.

[@bencushwa8902]

"*nucleotides ffs" - epic.

[@Garbaz]

6:04 "screwed" heh :)

[@whatshappenedhere1784]

I learnt a lot about nucleobases today, thanks Steve!

[@skydive701]

As a paramedic I use chiral versions of the same medicine with similar but not exact outcomes. Albuterol and Levalbuterol are both beta2 agonists and cause bronchial muscle relaxation. The main difference is the beta1 effects. Albuterol has beta1 agonist properties and will cause an increase in cardiac heart rate whereas the Levalbuterol does not cause as much of a rate increase. Both do work similar in their ability to relax the bronchial muscles allowing for asthmatic airways to open and help us humans breath a bit better

[@AdrianCuyubambaDiaz]

"Righty Tighty Lefty Loosey" We don't have a phrase like than in my language, it will come in handy 😉

[@vblaas246]

Both for electromagnetism (I to B and direction of current) and screws. They always forget to tell about the screws in and out of the plane. Then forget about the stupid and very useless right hand rule x)

[@nubnubbud]

I would say death stranding brought me here, but it just helped me know the words and concepts coming out of his mouth.

[@brightansparkly]

After watching this video I read Dorothy L Sayers' The Documents in the Case, a murder mystery whose solution rests on the chirality of a substance to determine whether it was man made or natural. Seeing the set up and recognising it from this video was pretty cool

[@KaeYoss]

A shop that only sells stuff for left-handed people? That sounds sinister!