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  • What I'm going to show you

  • are the astonishing molecular machines

  • that create the living fabric of your body.

  • Now molecules are really, really tiny.

  • And by tiny,

  • I mean really.

  • They're smaller than a wavelength of light,

  • so we have no way to directly observe them.

  • But through science, we do have a fairly good idea

  • of what's going on down at the molecular scale.

  • So what we can do is actually tell you about the molecules,

  • but we don't really have a direct way of showing you the molecules.

  • One way around this is to draw pictures.

  • And this idea is actually nothing new.

  • Scientists have always created pictures

  • as part of their thinking and discovery process.

  • They draw pictures of what they're observing with their eyes,

  • through technology like telescopes and microscopes,

  • and also what they're thinking about in their minds.

  • I picked two well-known examples,

  • because they're very well-known for expressing science through art.

  • And I start with Galileo

  • who used the world's first telescope

  • to look at the Moon.

  • And he transformed our understanding of the Moon.

  • The perception in the 17th century

  • was the Moon was a perfect heavenly sphere.

  • But what Galileo saw was a rocky, barren world,

  • which he expressed through his watercolor painting.

  • Another scientist with very big ideas,

  • the superstar of biology, is Charles Darwin.

  • And with this famous entry in his notebook,

  • he begins in the top left-hand corner with, "I think,"

  • and then sketches out the first tree of life,

  • which is his perception

  • of how all the species, all living things on Earth,

  • are connected through evolutionary history --

  • the origin of species through natural selection

  • and divergence from an ancestral population.

  • Even as a scientist,

  • I used to go to lectures by molecular biologists

  • and find them completely incomprehensible,

  • with all the fancy technical language and jargon

  • that they would use in describing their work,

  • until I encountered the artworks of David Goodsell,

  • who is a molecular biologist at the Scripps Institute.

  • And his pictures,

  • everything's accurate and it's all to scale.

  • And his work illuminated for me

  • what the molecular world inside us is like.

  • So this is a transection through blood.

  • In the top left-hand corner, you've got this yellow-green area.

  • The yellow-green area is the fluids of blood, which is mostly water,

  • but it's also antibodies, sugars,

  • hormones, that kind of thing.

  • And the red region is a slice into a red blood cell.

  • And those red molecules are hemoglobin.

  • They are actually red; that's what gives blood its color.

  • And hemoglobin acts as a molecular sponge

  • to soak up the oxygen in your lungs

  • and then carry it to other parts of the body.

  • I was very much inspired by this image many years ago,

  • and I wondered whether we could use computer graphics

  • to represent the molecular world.

  • What would it look like?

  • And that's how I really began. So let's begin.

  • This is DNA in its classic double helix form.

  • And it's from X-ray crystallography,

  • so it's an accurate model of DNA.

  • If we unwind the double helix and unzip the two strands,

  • you see these things that look like teeth.

  • Those are the letters of genetic code,

  • the 25,000 genes you've got written in your DNA.

  • This is what they typically talk about --

  • the genetic code -- this is what they're talking about.

  • But I want to talk about a different aspect of DNA science,

  • and that is the physical nature of DNA.

  • It's these two strands that run in opposite directions

  • for reasons I can't go into right now.

  • But they physically run in opposite directions,

  • which creates a number of complications for your living cells,

  • as you're about to see,

  • most particularly when DNA is being copied.

  • And so what I'm about to show you

  • is an accurate representation

  • of the actual DNA replication machine that's occurring right now inside your body,

  • at least 2002 biology.

  • So DNA's entering the production line from the left-hand side,

  • and it hits this collection, these miniature biochemical machines,

  • that are pulling apart the DNA strand and making an exact copy.

  • So DNA comes in

  • and hits this blue, doughnut-shaped structure

  • and it's ripped apart into its two strands.

  • One strand can be copied directly,

  • and you can see these things spooling off to the bottom there.

  • But things aren't so simple for the other strand

  • because it must be copied backwards.

  • So it's thrown out repeatedly in these loops

  • and copied one section at a time,

  • creating two new DNA molecules.

  • Now you have billions of this machine

  • right now working away inside you,

  • copying your DNA with exquisite fidelity.

  • It's an accurate representation,

  • and it's pretty much at the correct speed for what is occurring inside you.

  • I've left out error correction and a bunch of other things.

  • This was work from a number of years ago.

  • Thank you.

  • This is work from a number of years ago,

  • but what I'll show you next is updated science, it's updated technology.

  • So again, we begin with DNA.

  • And it's jiggling and wiggling there because of the surrounding soup of molecules,

  • which I've stripped away so you can see something.

  • DNA is about two nanometers across,

  • which is really quite tiny.

  • But in each one of your cells,

  • each strand of DNA is about 30 to 40 million nanometers long.

  • So to keep the DNA organized and regulate access to the genetic code,

  • it's wrapped around these purple proteins --

  • or I've labeled them purple here.

  • It's packaged up and bundled up.

  • All this field of view is a single strand of DNA.

  • This huge package of DNA is called a chromosome.

  • And we'll come back to chromosomes in a minute.

  • We're pulling out, we're zooming out,

  • out through a nuclear pore,

  • which is the gateway to this compartment that holds all the DNA

  • called the nucleus.

  • All of this field of view

  • is about a semester's worth of biology, and I've got seven minutes.

  • So we're not going to be able to do that today?

  • No, I'm being told, "No."

  • This is the way a living cell looks down a light microscope.

  • And it's been filmed under time-lapse, which is why you can see it moving.

  • The nuclear envelope breaks down.

  • These sausage-shaped things are the chromosomes, and we'll focus on them.

  • They go through this very striking motion

  • that is focused on these little red spots.

  • When the cell feels it's ready to go,

  • it rips apart the chromosome.

  • One set of DNA goes to one side,

  • the other side gets the other set of DNA --

  • identical copies of DNA.

  • And then the cell splits down the middle.

  • And again, you have billions of cells

  • undergoing this process right now inside of you.

  • Now we're going to rewind and just focus on the chromosomes

  • and look at its structure and describe it.

  • So again, here we are at that equator moment.

  • The chromosomes line up.

  • And if we isolate just one chromosome,

  • we're going to pull it out and have a look at its structure.

  • So this is one of the biggest molecular structures that you have,

  • at least as far as we've discovered so far inside of us.

  • So this is a single chromosome.

  • And you have two strands of DNA in each chromosome.

  • One is bundled up into one sausage.

  • The other strand is bundled up into the other sausage.

  • These things that look like whiskers that are sticking out from either side

  • are the dynamic scaffolding of the cell.

  • They're called mircrotubules. That name's not important.

  • But what we're going to focus on is this red region -- I've labeled it red here --

  • and it's the interface

  • between the dynamic scaffolding and the chromosomes.

  • It is obviously central to the movement of the chromosomes.

  • We have no idea really as to how it's achieving that movement.

  • We've been studying this thing they call the kinetochore

  • for over a hundred years with intense study,

  • and we're still just beginning to discover what it's all about.

  • It is made up of about 200 different types of proteins,

  • thousands of proteins in total.

  • It is a signal broadcasting system.

  • It broadcasts through chemical signals

  • telling the rest of the cell when it's ready,

  • when it feels that everything is aligned and ready to go

  • for the separation of the chromosomes.

  • It is able to couple onto the growing and shrinking microtubules.

  • It's involved with the growing of the microtubules,

  • and it's able to transiently couple onto them.

  • It's also an attention sensing system.

  • It's able to feel when the cell is ready,

  • when the chromosome is correctly positioned.

  • It's turning green here

  • because it feels that everything is just right.

  • And you'll see, there's this one little last bit

  • that's still remaining red.

  • And it's walked away down the microtubules.

  • That is the signal broadcasting system sending out the stop signal.

  • And it's walked away. I mean, it's that mechanical.

  • It's molecular clockwork.

  • This is how you work at the molecular scale.

  • So with a little bit of molecular eye candy,

  • we've got kinesins, which are the orange ones.

  • They're little molecular courier molecules walking one way.

  • And here are the dynein. They're carrying that broadcasting system.

  • And they've got their long legs so they can step around obstacles and so on.

  • So again, this is all derived accurately

  • from the science.

  • The problem is we can't show it to you any other way.

  • Exploring at the frontier of science,

  • at the frontier of human understanding,

  • is mind-blowing.

  • Discovering this stuff

  • is certainly a pleasurable incentive to work in science.

  • But most medical researchers --

  • discovering the stuff

  • is simply steps along the path to the big goals,

  • which are to eradicate disease,

  • to eliminate the suffering and the misery that disease causes

  • and to lift people out of poverty.

  • Thank you.

  • (Applause)

What I'm going to show you

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B2 H-INT US TED dna molecular chromosome strand copied

【TED】Drew Berry: Animations of unseeable biology (Drew Berry: Animations of unseeable biology)

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    何志豐   posted on 2016/05/31
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