0:00:02 > 0:00:05This is an egg. But not just any egg.
0:00:05 > 0:00:07The animal that will emerge from this can run
0:00:07 > 0:00:11at 70 kilometres an hour and will live for over 30 years.
0:00:11 > 0:00:14It's the world's largest bird, the ostrich.
0:00:14 > 0:00:19But how can an animal so large and complex come from something so simple?
0:00:19 > 0:00:22We all do it. We all begin life as a single cell.
0:00:22 > 0:00:25And turn into...us!
0:00:25 > 0:00:27But how do we do it?
0:00:27 > 0:00:30This remarkable transformation
0:00:30 > 0:00:32is one of the most exciting mysteries on earth.
0:00:32 > 0:00:35It's life fantastic.
0:01:01 > 0:01:03Have you ever stopped to think...
0:01:03 > 0:01:08Have you ever stopped to think about how extraordinary you are?
0:01:08 > 0:01:10Turn and look at your neighbour.
0:01:10 > 0:01:12You're looking at them with your eyes
0:01:12 > 0:01:14and their eyes are looking back at you.
0:01:14 > 0:01:16How does that work?
0:01:16 > 0:01:19How does your brain coordinate all that stuff?
0:01:19 > 0:01:22Turn the other way and look at your other neighbour.
0:01:22 > 0:01:24How did you just do that?
0:01:24 > 0:01:27How did your brain know to coordinate all your muscles,
0:01:27 > 0:01:31contracting, to turn your head, just when you wanted to?
0:01:32 > 0:01:33You're amazing.
0:01:33 > 0:01:36And you're amazing
0:01:36 > 0:01:38and you're amazing.
0:01:38 > 0:01:41In fact, we're all amazing.
0:01:41 > 0:01:45We're all amazing because we're all hugely complicated machines
0:01:45 > 0:01:52made up of, wait for it, 40 trillion cells.
0:01:52 > 0:01:54Cells are the basic building blocks of life.
0:01:54 > 0:02:00But can we imagine what 40 trillion of anything actually looks like?
0:02:00 > 0:02:02MACHINE HISSES LOUDLY
0:02:11 > 0:02:12Wow!
0:02:12 > 0:02:14LAUGHTER
0:02:14 > 0:02:16That was only 200,000!
0:02:17 > 0:02:20If they were cells, that's nowhere near enough to make a person,
0:02:20 > 0:02:26so we would need 200 million of these confetti cannons
0:02:26 > 0:02:29to make 40 trillion pieces of confetti.
0:02:31 > 0:02:34Or, put it another way. To see 40 trillion pieces of confetti,
0:02:34 > 0:02:38we'd have to repeat an explosion like this once every second
0:02:38 > 0:02:41for, wait for it, can anyone guess how long?
0:02:43 > 0:02:482,314 days.
0:02:48 > 0:02:51That's about six years.
0:02:51 > 0:02:53Where do all these 40 trillion cells come from,
0:02:53 > 0:02:57and how on earth do they all know what to do?
0:02:57 > 0:03:02Welcome to the 2013 Royal Institution Christmas lectures.
0:03:02 > 0:03:06My name is Alison Woollard and I'm a developmental biologist
0:03:06 > 0:03:10and today, you're coming with me on an adventure through life fantastic,
0:03:10 > 0:03:14to see how these trillions of cells come together to make you.
0:03:14 > 0:03:16So let's have a look at you.
0:03:16 > 0:03:18I've got two of you here. Up here.
0:03:18 > 0:03:21And I think you're in the audience this evening.
0:03:21 > 0:03:24Can you identify yourselves?
0:03:24 > 0:03:27Ah! Thank you very much. Come down, let's have a chat.
0:03:27 > 0:03:28APPLAUSE
0:03:32 > 0:03:36So, if you could just stand here so everyone can see how lovely you are.
0:03:36 > 0:03:40Thank you very much. What are your names? I'm Chris. Kavita. Kavita.
0:03:40 > 0:03:42Thank you for giving us your photos.
0:03:42 > 0:03:45And would you confirm for us that these are in fact you?
0:03:45 > 0:03:47And how old are you here? 13.
0:03:47 > 0:03:50You're 13. And you're? 15. 15.
0:03:50 > 0:03:52So this is you at 15 and you at 13.
0:03:52 > 0:03:55OK? So what we're going to do now is, we're going to wind the clock back.
0:03:55 > 0:03:58Do you want to come out a little bit further
0:03:58 > 0:04:01so that you can see yourselves going backwards through your development.
0:04:01 > 0:04:05The next picture will show what you were like when you were five.
0:04:05 > 0:04:08Oh, that's very nice. I know. Was that your party? It was, yeah.
0:04:08 > 0:04:12Very nice. Were those hats to cover your horns? Um, yeah!
0:04:12 > 0:04:12Very nice. Were those hats to cover your horns? Um, yeah!
0:04:12 > 0:04:15And you're looking very lovely as well, Kavita.
0:04:15 > 0:04:20Let's wind the clock back again, 18 months. Aww! Really, really sweet.
0:04:20 > 0:04:24And if you keep winding the clock back, let's go back again.
0:04:24 > 0:04:26There you both are as newborn babies.
0:04:26 > 0:04:28And, we can go back a bit further than that,
0:04:28 > 0:04:30cos we can look to see what you were like,
0:04:30 > 0:04:33this is when you were in your mums' tummies. 20 weeks.
0:04:33 > 0:04:35About halfway through your development.
0:04:35 > 0:04:38But, we can keep winding the clock back.
0:04:38 > 0:04:42This is what someone like you would have looked like at about five weeks of development.
0:04:42 > 0:04:44Does that look like you?
0:04:44 > 0:04:46Have you got your Uncle Bert's ears?
0:04:46 > 0:04:49I don't think so, not at the moment, no. Your dad's nose?
0:04:49 > 0:04:51Hard to tell, isn't it? Let's go back again. This is four weeks.
0:04:51 > 0:04:54Things are looking very different now, aren't they?
0:04:54 > 0:04:57Let's go back again...
0:04:57 > 0:05:00to a little ball of cells. Aw!
0:05:00 > 0:05:05And back again, to this. This is where you all started.
0:05:05 > 0:05:07This is a single cell.
0:05:07 > 0:05:11An egg cell that's just been fertilised by your dad's sperm.
0:05:11 > 0:05:13So, what would you say are the most complicated bits?
0:05:13 > 0:05:16Where does the drama happen in your development?
0:05:16 > 0:05:19Has it just happened at the age of 11-13, do you think,
0:05:19 > 0:05:22or is it the earlier stages?
0:05:22 > 0:05:23What would you say?
0:05:23 > 0:05:26Probably the earlier stages. I would agree.
0:05:26 > 0:05:29All the drama happens in those nine short months
0:05:29 > 0:05:31of your early development.
0:05:31 > 0:05:35Thank you so much for sharing your life history with us this evening.
0:05:35 > 0:05:36Please go and sit down.
0:05:36 > 0:05:38APPLAUSE
0:05:43 > 0:05:48So how exactly does one cell, this one cell, for example,
0:05:48 > 0:05:50become 40 trillion?
0:05:50 > 0:05:53This bit isn't too complicated, actually,
0:05:53 > 0:05:56because cells have the remarkable ability to split themselves
0:05:56 > 0:06:00into two exact halves called daughter cells.
0:06:00 > 0:06:02Funny, you know, developmental biology is very feminist.
0:06:02 > 0:06:04We talk about daughter cells and mother cells.
0:06:04 > 0:06:07We never talk about sons and fathers.
0:06:07 > 0:06:08So, daughter cells.
0:06:08 > 0:06:12And those daughter cells, in turn, can divide themselves in half.
0:06:12 > 0:06:15And this carries on, so, shall we picture the scene?
0:06:15 > 0:06:18I believe you've been trained with some glow sticks.
0:06:18 > 0:06:21There should be one of you in row three, is that you? Yeah.
0:06:21 > 0:06:23With a glow stick. What's your name? Eleanor.
0:06:23 > 0:06:26Eleanor, thank you so much for agreeing to do this for us this evening.
0:06:26 > 0:06:30You have one glow stick that signifies that first cell.
0:06:30 > 0:06:34And your cell is going to, let's get it lit up, shall we? OK.
0:06:34 > 0:06:37That's the way. Oh, they're nice and bright, aren't they?
0:06:37 > 0:06:39So, what's going to happen is, I'm going to say "divide".
0:06:39 > 0:06:42Does this sound familiar? I'm going to say "divide",
0:06:42 > 0:06:43and you're going to divide,
0:06:43 > 0:06:47so, you're going to go to the row behind, and the row behind that,
0:06:47 > 0:06:48and the row behind that.
0:06:48 > 0:06:51And that will show us what's happening as that first,
0:06:51 > 0:06:52original cell starts to divide.
0:06:52 > 0:06:56OK, ready? Divide.
0:06:56 > 0:07:00And divide.
0:07:00 > 0:07:05And divide again.
0:07:05 > 0:07:06And divide.
0:07:07 > 0:07:10Brilliant, fantastic.
0:07:12 > 0:07:15We may have lost one or two cells along the way,
0:07:15 > 0:07:16but it doesn't really matter.
0:07:16 > 0:07:20We've ended up with 64, and we came from one,
0:07:20 > 0:07:22and that all happened quite quickly, didn't it?
0:07:22 > 0:07:25And, actually, if this lecture theatre was a bit bigger,
0:07:25 > 0:07:26and we had a few more seats, so,
0:07:26 > 0:07:31if we extended the lecture theatre out into Albemarle Street, by
0:07:31 > 0:07:35the end of the 10th row, we'd have 512 of these glow sticks, or cells.
0:07:35 > 0:07:40And, by the end of row 20, we'd have half a million.
0:07:40 > 0:07:44And by the end of row 45, we'd have the 40 trillion lights,
0:07:44 > 0:07:48or cells, that we would need to build a human.
0:07:48 > 0:07:51So, you can see that the numbers get very quick, very quickly,
0:07:51 > 0:07:53when we're talking about cells doubling.
0:07:53 > 0:07:58And I don't know about you, but 45 cells doubling seems
0:07:58 > 0:08:03like a relatively small number to get to 40 trillion cells.
0:08:03 > 0:08:05Right, enough of all these numbers.
0:08:05 > 0:08:09Let's look at some real cell divisions in some real organisms.
0:08:09 > 0:08:14It's time to introduce you, ladies and gentlemen, to my hero organism.
0:08:14 > 0:08:19And my hero organism is in this box. Really exciting.
0:08:19 > 0:08:21Are you ready for this? Whoa!
0:08:21 > 0:08:24What do you think? Huh? Impressed?
0:08:24 > 0:08:26You don't look very impressed.
0:08:26 > 0:08:29Because these are rotten apples. Would anyone like one?
0:08:29 > 0:08:31No.
0:08:31 > 0:08:34I wouldn't recommend it. They're a bit smelly.
0:08:34 > 0:08:35Now, I don't work on rotten apples.
0:08:35 > 0:08:39I work on something that lives in this box WITH the apples,
0:08:39 > 0:08:42and likes to eat them. Do you know what that might be?
0:08:42 > 0:08:45Anyone like to guess? Yes?
0:08:45 > 0:08:47Bacteria, well, there's lots of bacteria in that box, yes,
0:08:47 > 0:08:50but that's not what I work on. What about you?
0:08:50 > 0:08:51Worms?
0:08:51 > 0:08:52Sorry?
0:08:52 > 0:08:56Worms? Yes! Brilliant! Worms.
0:08:56 > 0:09:00Actually, a very small worm called Caenorhabditis elegans.
0:09:00 > 0:09:04We call it C elegans for short. It's a nematode worm.
0:09:04 > 0:09:06And actually, when we work on them in the lab,
0:09:06 > 0:09:10we don't have big boxes of smelly rotten apples lying around.
0:09:10 > 0:09:15We grow them on these nice, clean plates, these Petri dishes.
0:09:15 > 0:09:20And if I hold this plate up to the light, and to the camera,
0:09:20 > 0:09:25you should see some tiny, little white threads
0:09:25 > 0:09:27about a millimetre long.
0:09:27 > 0:09:31And those little, tiny white threads are the worms, C elegans.
0:09:32 > 0:09:33And I'm going to hand some plates around to you now,
0:09:33 > 0:09:35And I'm going to hand some plates around to you now,
0:09:35 > 0:09:38so you can have a look, you can hold them up to the light yourself.
0:09:38 > 0:09:41I've Parafilmed the plates so that you don't put your fingers in them
0:09:41 > 0:09:42and get squishy worms all over them.
0:09:42 > 0:09:48So they're very safe. So, let's just hand some of these plates out.
0:09:48 > 0:09:51You can just pass them around, and have a look at your leisure.
0:09:51 > 0:09:54Now, these worms are a little bit small, aren't they?
0:09:54 > 0:09:58So, we really need some help to see them. We need a microscope.
0:09:58 > 0:10:01And here's some microscopes over here.
0:10:01 > 0:10:03And we're going to start by showing a video that we recorded
0:10:03 > 0:10:08a little bit earlier on, of some worms crawling around on the plates.
0:10:08 > 0:10:11So, here they are. Here's our C elegans. And here's Mum,
0:10:11 > 0:10:14coming through the middle, looking a bit bossy.
0:10:14 > 0:10:17And she has the babies all around her, so we can see
0:10:17 > 0:10:21worms of different sizes. The little oval things are embryos.
0:10:21 > 0:10:24They're the next generation of worms forming.
0:10:24 > 0:10:27And we can see immediately how useful these animals are
0:10:27 > 0:10:29because they're transparent.
0:10:29 > 0:10:31And that means that we can see inside them.
0:10:31 > 0:10:35And we can see all the cells in this animal.
0:10:35 > 0:10:37There are about 1,000 cells altogether.
0:10:37 > 0:10:39And, if you're a real geek, like me, you can
0:10:39 > 0:10:41actually recognise each one of them. OK?
0:10:41 > 0:10:44But it means that we can study development
0:10:44 > 0:10:49by just looking at the animals very, very closely.
0:10:49 > 0:10:54And these tiny worms have so much to tell us about the mysteries of life.
0:10:54 > 0:10:57And I can see you thinking, "What's she talking about? They're worms.
0:10:57 > 0:11:02"What does that, how does that tell us about OUR development?"
0:11:02 > 0:11:03Let me show you something.
0:11:03 > 0:11:08I want you to look at these pictures of embryos.
0:11:08 > 0:11:12These are all embryos not very far into their development.
0:11:12 > 0:11:16And they're all looking pretty similar, really, aren't they?
0:11:16 > 0:11:20Well, let's reveal what they're going to develop into.
0:11:20 > 0:11:26What are they going to... Wow! Rather different things. OK?
0:11:26 > 0:11:28We've got a human, we've got a mouse, we've got
0:11:28 > 0:11:32a sea urchin down there, and we've got my hero worm.
0:11:32 > 0:11:35We just put a bit of DAPI stain in there,
0:11:35 > 0:11:37to see the DNA of these worms.
0:11:37 > 0:11:41But you can see that you get very, very different outcomes
0:11:41 > 0:11:43from these rather similar beginnings.
0:11:43 > 0:11:47And that's really useful to us, because it tells us that,
0:11:47 > 0:11:49if we're interested in the development of
0:11:49 > 0:11:51a complicated organism like ourselves,
0:11:51 > 0:11:53or like the mouse, for example,
0:11:53 > 0:11:57then we can look at these processes in much simpler organisms,
0:11:57 > 0:12:01like worms and, because the processes of development
0:12:01 > 0:12:04are quite similar, it's all about cells multiplying
0:12:04 > 0:12:06and then working out what to do,
0:12:06 > 0:12:09and going to the right place and doing it, it means that
0:12:09 > 0:12:13we can study those processes in these very simple organisms,
0:12:13 > 0:12:18and then apply what we learn to our own biology.
0:12:18 > 0:12:21So, that's the power of model organisms.
0:12:21 > 0:12:23And it makes sense to study worms, as they go through
0:12:23 > 0:12:26these very similar developmental processes to us.
0:12:26 > 0:12:29And yet, they develop much faster,
0:12:29 > 0:12:31so we can see things happening much more quickly.
0:12:31 > 0:12:36So, how fast? Can it happen right in front of us, right now?
0:12:36 > 0:12:39Shall we create life, here, in the lecture theatre this evening?
0:12:40 > 0:12:45Well, we can't create human life, but we can create worm life.
0:12:45 > 0:12:47So let's get started.
0:12:47 > 0:12:50My assistant, here, Peter has chosen for us some early embryos
0:12:50 > 0:12:55and we are looking at them developing live in front of us.
0:12:55 > 0:12:57So here, we have a two-cell embryo.
0:12:57 > 0:13:00It's just gone through its very first division.
0:13:00 > 0:13:04This is a really, really, really young worm.
0:13:04 > 0:13:08And we're going to leave this running. It's our worm cam.
0:13:08 > 0:13:10We're going to leave it running throughout the lecture,
0:13:10 > 0:13:12and you'll start to see things happening to this.
0:13:12 > 0:13:15And when something happens, I want you to tell me,
0:13:15 > 0:13:17because I might not be looking at it properly.
0:13:17 > 0:13:19And if you see something big happening,
0:13:19 > 0:13:21like a cell dividing, just shout out,
0:13:21 > 0:13:22and we can go back to it.
0:13:22 > 0:13:25And we can also, we'll be recording, as well,
0:13:25 > 0:13:29so we can go back and we can look at anything we might have missed.
0:13:29 > 0:13:34And Pete, here, is going to keep score on his worm division scoreboard,
0:13:34 > 0:13:38so, every time a cell divides, we're going to move on a number.
0:13:38 > 0:13:42So make sure that you tell us when this happens, OK?
0:13:42 > 0:13:45So, this is what gets developmental biologists like me
0:13:45 > 0:13:47out of bed in the morning.
0:13:47 > 0:13:50This is amazing because this is a new worm
0:13:50 > 0:13:53being made right in front of us. OK?
0:13:53 > 0:13:56You can't do that with a lot of organisms, but you can do it
0:13:56 > 0:14:00with C elegans, because it's so easy to see this happening
0:14:00 > 0:14:02under quite a simple microscope.
0:14:02 > 0:14:05And we want to understand this amazing process.
0:14:05 > 0:14:09How does an organism develop from an egg to an adult?
0:14:09 > 0:14:11How is this controlled?
0:14:11 > 0:14:14And how do our studies in these simple model organisms
0:14:14 > 0:14:18shed light on our own development, and what can go wrong?
0:14:18 > 0:14:21So, life, even though it's happening right in front of us,
0:14:21 > 0:14:24it's little bit slow, and we've got a speeded up film to show you,
0:14:24 > 0:14:26as well, to see what happens a bit later on
0:14:26 > 0:14:28in the development of the worm.
0:14:28 > 0:14:30So we've got one we prepared earlier.
0:14:30 > 0:14:33And we can see all these cell divisions going on
0:14:33 > 0:14:35and we're building up a ball of cells here, quite rapidly,
0:14:35 > 0:14:38and then, what's going to happen is, that ball of cells is going
0:14:38 > 0:14:41to reorganise itself into a three-dimensional thing.
0:14:41 > 0:14:42to reorganise itself into a three-dimensional thing.
0:14:42 > 0:14:46And we can see that start to happen. It's called morphogenesis.
0:14:46 > 0:14:47That's the acquisition of form.
0:14:47 > 0:14:50And you can see, this ball of cells has reorganised
0:14:50 > 0:14:53itself into something that looks a little bit more like a worm.
0:14:53 > 0:14:54And it's hard to see what's going on now
0:14:54 > 0:14:58because the muscle cells in this one have started twitching,
0:14:58 > 0:15:00because they've suddenly realised that they're muscle cells,
0:15:00 > 0:15:02and twitching is what muscle cells do.
0:15:02 > 0:15:04But we can see something now.
0:15:04 > 0:15:07We're getting towards the end of the embryonic development stage,
0:15:07 > 0:15:12and this is a little worm about to hatch out of its eggshell
0:15:12 > 0:15:14and start its life as a worm.
0:15:14 > 0:15:15So this tells us, then, that we are not just bags of disorganised cells.
0:15:15 > 0:15:19So this tells us, then, that we are not just bags of disorganised cells.
0:15:19 > 0:15:24In development, cells must cooperate to form tissues and organs.
0:15:24 > 0:15:29They come together to make complicated bits.
0:15:29 > 0:15:30Like this!
0:15:32 > 0:15:37Now, this is not worm. This is a cow's leg.
0:15:37 > 0:15:40I'm sure that this is quite obvious that this is not a worm.
0:15:40 > 0:15:43And we can see all sorts of bits in here. We can see bone in the middle.
0:15:43 > 0:15:46We've got muscle, here. We've got a bit of fat around the outside.
0:15:46 > 0:15:48We've got connective tissue.
0:15:48 > 0:15:52They've removed the skin, but we can see all these things.
0:15:52 > 0:15:55We can see some blood, here, dripping away.
0:15:55 > 0:15:59So, this tells us, then, that we only have to look inside one
0:15:59 > 0:16:04bit of a body to see that it's composed of lots of different bits.
0:16:04 > 0:16:05And, all these bits, all these cells, are doing different things,
0:16:06 > 0:16:09And, all these bits, all these cells, are doing different things,
0:16:09 > 0:16:11but they're all doing it in the right pattern.
0:16:11 > 0:16:15In order to make this whole limb that works properly.
0:16:15 > 0:16:18Thank you very much. Time to go and put that in the oven, I think.
0:16:18 > 0:16:22Let's look at some more examples of cells working together in harmony.
0:16:22 > 0:16:25I think Hayley, here, has got something else to show us.
0:16:26 > 0:16:29Hayley, thank you for coming. What have you brought for us?
0:16:29 > 0:16:31Shall we have a look? Yes, please.
0:16:33 > 0:16:37Gosh! What's that? Let's have a look.
0:16:37 > 0:16:40Does anyone know what that is?
0:16:40 > 0:16:43Yes? Shout.
0:16:43 > 0:16:44AUDIENCE: A heart!
0:16:44 > 0:16:46Gosh, you're all very good, aren't you?
0:16:46 > 0:16:48This audience, all very bright, I can tell.
0:16:48 > 0:16:50So, yes, that's a heart.
0:16:50 > 0:16:53What are you doing, putting it...? That's the dorsal aorta.
0:16:53 > 0:16:56So, the heart is a pumping organ.
0:16:56 > 0:17:00Very important for pumping blood around our bodies
0:17:00 > 0:17:03so that it delivers oxygen to all of our tissues.
0:17:03 > 0:17:07And the average heart beats 100,000 times a day.
0:17:07 > 0:17:10No wonder we're all tired when we go to bed at night.
0:17:10 > 0:17:14That's more than 35 million times a year.
0:17:14 > 0:17:16Thank you, Hayley. What's that in the middle, there?
0:17:17 > 0:17:20Ugh! Goodness me. What's that?
0:17:20 > 0:17:22Let's see. Hold it up. Let's have a look.
0:17:23 > 0:17:25Does anyone know what this might be?
0:17:25 > 0:17:26Yes, shout at me.
0:17:26 > 0:17:29AUDIENCE: Lungs. Lungs, yes!
0:17:29 > 0:17:31It's got a funny little pipe sticking out of it.
0:17:31 > 0:17:33We're going to use that in a minute.
0:17:33 > 0:17:36But, the lung is an inflatable organ that you breathe with.
0:17:36 > 0:17:40It has 1,500 miles of airways in it.
0:17:40 > 0:17:44That's the distance from here to beyond Rome, OK?
0:17:44 > 0:17:47And it has a huge surface area.
0:17:47 > 0:17:51So, if we spread out this lung, so we used all its surface area,
0:17:51 > 0:17:54it would take up about half a tennis court.
0:17:54 > 0:17:56OK? In fact, I can't resist it.
0:17:56 > 0:17:59We're going to have to blow it up, we're going to have to inflate it.
0:17:59 > 0:18:01Can I have a volunteer to help with this?
0:18:01 > 0:18:03Yes, would you like to come down? Thank you.
0:18:07 > 0:18:09Right.
0:18:09 > 0:18:10OK, put those on.
0:18:10 > 0:18:13Don't I get any safety glasses?
0:18:13 > 0:18:14What's your name? Tom.
0:18:14 > 0:18:17Right, could you turn round so everyone can see how lovely you are?
0:18:17 > 0:18:21Now, Tom, I'm not going to ask you to put any tubes in your mouth
0:18:21 > 0:18:24and blow, because the chances are, you might suck as well,
0:18:24 > 0:18:25and that wouldn't be good!
0:18:25 > 0:18:29What we do have is a nice little pump here.
0:18:29 > 0:18:31That you should be able to use.
0:18:31 > 0:18:33Are we good to go, Hayley? Right.
0:18:33 > 0:18:34Not too heavy.
0:18:34 > 0:18:37Not too heavy, right. We have a bit of a...
0:18:37 > 0:18:40With your foot, I think. Yeah, with your foot. See what happens.
0:18:40 > 0:18:44Oh, it's going. Keep going. Can everyone see that?
0:18:44 > 0:18:45Oh, it's going. Keep going. Can everyone see that?
0:18:45 > 0:18:47Give it a few rapid bursts.
0:18:47 > 0:18:52Yes, we're inflating our lungs. Look at that. We're inflating our lungs.
0:18:52 > 0:18:56You're very good at this, aren't you? Inflating our lungs quite well.
0:18:56 > 0:18:58Thank you, thank you so much for doing that.
0:18:58 > 0:19:02If you'd like to go and sit down. Thank you very much, Tom.
0:19:09 > 0:19:15And what's the final organ we've got here today? I can't guess. Ooh!
0:19:15 > 0:19:22Ah, yes! Let's have a look at this. Does anyone know what it is?
0:19:22 > 0:19:23Yes, shout.
0:19:23 > 0:19:24AUDIENCE: Brain.
0:19:24 > 0:19:24AUDIENCE: Brain.
0:19:24 > 0:19:25Whose brain is it?
0:19:25 > 0:19:29Did anyone donate their brain this evening? You did, did you?
0:19:29 > 0:19:32Brains are in charge of everything, so they're full of neurons
0:19:32 > 0:19:35that connect with each other and help us make decisions
0:19:35 > 0:19:37about everything that we do.
0:19:39 > 0:19:42So, all of these organs look... Thank you, Hayley, that's brilliant.
0:19:42 > 0:19:45All of these organs look very different,
0:19:45 > 0:19:47and they have very different jobs.
0:19:47 > 0:19:49They're all composed of cells, aren't they?
0:19:49 > 0:19:52So cells must look quite different from one another
0:19:52 > 0:19:55in order for these organs to look at one another,
0:19:55 > 0:19:58so let's have a look at some cells, shall we?
0:19:58 > 0:20:00The first cell type we're going to look at,
0:20:00 > 0:20:03does anyone know what these are?
0:20:03 > 0:20:05Ooh! Yes, what do you think?
0:20:05 > 0:20:06Nerve endings?
0:20:06 > 0:20:08Nerve endings? Yes.
0:20:10 > 0:20:11Neurons.
0:20:11 > 0:20:13Neurons, yes. Why do you say that?
0:20:13 > 0:20:21Because, they were long and spindly and had lighty-up sort of blobs.
0:20:21 > 0:20:26Yes, and that's because they form these intricate connections
0:20:26 > 0:20:30with each other and with muscle cells, and so on.
0:20:30 > 0:20:33And that's absolutely crucial for our brains to work
0:20:33 > 0:20:35and our nervous systems to work.
0:20:35 > 0:20:39So neurons are really beautiful cells, and that's their job.
0:20:39 > 0:20:41Let's have a look at the next cell type.
0:20:41 > 0:20:43Now, does anyone know what these might be?
0:20:45 > 0:20:47Yes? Blood cells?
0:20:47 > 0:20:50Sorry? Blood cells? Well, actually, there are some blood cells on here,
0:20:50 > 0:20:52but they've kind of sneaked on.
0:20:52 > 0:20:55We have got some blood cells in there, yes.
0:20:55 > 0:20:57INAUDIBLE RESPONSE
0:20:57 > 0:21:00They're ciliated, well spotted. Biologist in the making over there!
0:21:00 > 0:21:05They're actually lung cells. Does anyone have a cold at the moment?
0:21:05 > 0:21:09Are you doing a lot of coughing? Are you coughing up loads of gunk? Yes?
0:21:09 > 0:21:11Well, your using your lung cells a lot.
0:21:11 > 0:21:15Because your lung cells have these hairs, these cilia, in them,
0:21:15 > 0:21:19that act as kind of brooms, and sweep all the gunk
0:21:19 > 0:21:23and all the phlegm along so that you can cough it all out of your lungs.
0:21:23 > 0:21:26So, a very useful cell type indeed.
0:21:26 > 0:21:31And the next cell type, the next cell type we're going to look at
0:21:31 > 0:21:35is so special that it comes with its own handler.
0:21:38 > 0:21:42Welcome, Beata, thank you for coming.
0:21:42 > 0:21:45So, Beata, what have you brought for us this evening?
0:21:45 > 0:21:49Oh, wow, look at them. Can we see those up on the screen now?
0:21:49 > 0:21:52Can everybody see? What are these cells doing?
0:21:52 > 0:21:55They're forming a big clump, but what are they doing together?
0:21:57 > 0:22:01Can anyone see what these cells are doing together?
0:22:01 > 0:22:03What's that? Yes? They're moving.
0:22:03 > 0:22:07What kind of movement do you think it might be?
0:22:07 > 0:22:09I thought they were pulsing.
0:22:09 > 0:22:11Pulsing? Yes?
0:22:11 > 0:22:12Er, beating?
0:22:12 > 0:22:15They're beating! Excellent, well done.
0:22:15 > 0:22:17So, what kind of cells do you think these might be?
0:22:17 > 0:22:19Heart cells?
0:22:19 > 0:22:22Heart cells, exactly, beating heart cells.
0:22:22 > 0:22:26So, Beata, tell me how you got these cells to us this evening.
0:22:26 > 0:22:26So, to make these cardiomyocytes,
0:22:27 > 0:22:27So, to make these cardiomyocytes,
0:22:27 > 0:22:31what scientists do is they use very young cells, called stem cells
0:22:31 > 0:22:33and this is actually so young
0:22:33 > 0:22:36that they can differentiate to any cell in our body,
0:22:36 > 0:22:39so what we can do nowadays, we can instruct these young cells
0:22:39 > 0:22:41to become cardiomyocytes,
0:22:41 > 0:22:44when we use different factors and methods at the same time.
0:22:44 > 0:22:48So, we've got these cells growing in a Petri dish,
0:22:48 > 0:22:53nowhere near a heart, and yet they know that they should be beating
0:22:53 > 0:22:57like heart cells, and they carry on doing that in their Petri dish.
0:22:57 > 0:23:00I think that's amazing. How long will they do that for?
0:23:00 > 0:23:03Probably for just a few minutes. Oh, just a few minutes.
0:23:03 > 0:23:05We were lucky, then, weren't we?
0:23:05 > 0:23:10And I can see that these might have some point in medicine.
0:23:10 > 0:23:14Yeah, these cells are very important because these are very similar
0:23:14 > 0:23:17to the cells that we've got in our heart, which means that
0:23:17 > 0:23:19we can use them, for example, when we have got a heart attack,
0:23:19 > 0:23:21so when the heart is injured.
0:23:21 > 0:23:22Or also, we can use these cells to test new medicines.
0:23:22 > 0:23:25Or also, we can use these cells to test new medicines.
0:23:25 > 0:23:28We're just pausing for a minute to go to worm cam.
0:23:28 > 0:23:31Because little worm embryo over there has done something exciting.
0:23:31 > 0:23:34It's done another cell division, just about to.
0:23:34 > 0:23:38This cell here is just about to split into two, and we can actually
0:23:38 > 0:23:41see this cleared area here in the middle is the nuclei pulling apart.
0:23:41 > 0:23:45This is happening, live. We didn't know that was about to happen then.
0:23:45 > 0:23:50So, could you actually build a whole heart?
0:23:50 > 0:23:52We hope that one day this will be possible.
0:23:52 > 0:23:56However, there is more to a whole organ, like a heart, than just
0:23:56 > 0:23:58the cells in a dish, as there are all very important
0:23:58 > 0:24:02cells types in the heart as well, that play crucial roles.
0:24:02 > 0:24:03But that would be amazing, wouldn't it?
0:24:03 > 0:24:06Think what you could do to heart transplants
0:24:06 > 0:24:08if you could grow hearts in the lab.
0:24:08 > 0:24:11There'd be no queues for transplants.
0:24:11 > 0:24:14And it would also mean that the patients who need a heart
0:24:14 > 0:24:18could have a new heart grown for them from their own stem cells.
0:24:18 > 0:24:20Another one's at it now, isn't it?
0:24:20 > 0:24:23The other cell's starting to divide, yes.
0:24:23 > 0:24:26So, things are happening in our worm.
0:24:26 > 0:24:27Beata, thank you so much
0:24:27 > 0:24:30for sharing these cardiomyocytes with us this evening.
0:24:30 > 0:24:31Beata.
0:24:34 > 0:24:37So, looking at all these different types of cell, then,
0:24:37 > 0:24:40we can see how different organs might be generated.
0:24:40 > 0:24:43But what is it that gives each different type of cell
0:24:43 > 0:24:46its distinct properties?
0:24:46 > 0:24:49What makes a neuron different from a heart cell?
0:24:49 > 0:24:52Well, the answer to this is proteins.
0:24:52 > 0:24:56It's the type of proteins that the cell produces.
0:24:56 > 0:24:58And I can show you some proteins now
0:24:58 > 0:25:03with the help of my special gestural interface machine here.
0:25:03 > 0:25:07So, we can see that proteins on one level are quite simple molecules.
0:25:07 > 0:25:12They consist of carbon, hydrogen, oxygen, nitrogen,
0:25:12 > 0:25:17a bit of sulphur thrown in. Their basic units are amino acids.
0:25:17 > 0:25:19There's 20 amino acids together.
0:25:19 > 0:25:21But these are strung together completely differently
0:25:21 > 0:25:23in different proteins,
0:25:23 > 0:25:26and that gives all these different proteins a staggering
0:25:26 > 0:25:28diversity in terms of their shape.
0:25:28 > 0:25:33And I think I can get control of these proteins now
0:25:33 > 0:25:37just by moving my hands, by trickery of modern technology.
0:25:37 > 0:25:41And we can look all around these different proteins.
0:25:41 > 0:25:46The first one I want to show you in detail is called myosin.
0:25:46 > 0:25:50This is a protein that you find in muscle.
0:25:50 > 0:25:54And if we look at it like that we can see that it has
0:25:54 > 0:25:57a particular shape, that includes a tail.
0:25:57 > 0:26:02And myosin is really important to help our muscles move.
0:26:02 > 0:26:06And that's because this tail helps the protein do this job.
0:26:06 > 0:26:09And the structure of myosin can bend and straighten itself, and this
0:26:09 > 0:26:15bending and straightening creates the force required for movement.
0:26:15 > 0:26:16So that's myosin.
0:26:16 > 0:26:21The next protein we can look at here is called haemoglobin.
0:26:21 > 0:26:23This is an oxygen-carrying molecule,
0:26:23 > 0:26:26so it carries oxygen around the blood.
0:26:26 > 0:26:28And the shape of haemoglobin is so important
0:26:28 > 0:26:32because when one molecule of oxygen binds to the haemoglobin protein,
0:26:32 > 0:26:34it actually changes the shape
0:26:34 > 0:26:38and that encourages more molecules of oxygen to bind.
0:26:38 > 0:26:40It's called cooperative binding.
0:26:40 > 0:26:43And so you can imagine what an efficient
0:26:43 > 0:26:47carrier of oxygen in our blood this is.
0:26:47 > 0:26:50And so this is the reason why our different cells look
0:26:50 > 0:26:52and behave in such different ways.
0:26:52 > 0:26:55They all contain different shaped proteins.
0:26:55 > 0:26:58In fact, this is one of the big secrets of life.
0:26:59 > 0:27:01OK, enough of all these protein models.
0:27:01 > 0:27:05Shall we see a protein in action?
0:27:05 > 0:27:08Ollie, are you there? Thank you, come on down.
0:27:10 > 0:27:12Ollie, would you just like to stand
0:27:12 > 0:27:14and show the audience your wonderful machine?
0:27:14 > 0:27:17I understand this is a vein viewer. Yes.
0:27:17 > 0:27:19So we'll be able to view veins.
0:27:19 > 0:27:21Shall we give it a go? Switch it on...
0:27:21 > 0:27:24Can I have a look at your arm? Ah, here we are.
0:27:26 > 0:27:30With this machine, we can actually look inside Ollie's body
0:27:30 > 0:27:34without chopping him up, which is just as well, really.
0:27:34 > 0:27:37Can you see that?
0:27:37 > 0:27:41So, this is the blood inside Ollie's veins.
0:27:41 > 0:27:44And this is an incredibly useful machine,
0:27:44 > 0:27:47because when people are learning to take blood in hospital,
0:27:47 > 0:27:50they can use this to see exactly where a patient's
0:27:50 > 0:27:53veins are without poking them around with a needle.
0:27:53 > 0:27:56So this is a really, really clever machine.
0:27:56 > 0:28:00And what we're looking at here is this haemoglobin protein
0:28:00 > 0:28:03that's rushing around inside Ollie's veins.
0:28:03 > 0:28:06Shall we see if you've got any veins in your neck?
0:28:06 > 0:28:09You should have, let's check.
0:28:09 > 0:28:13There we are, lots of... Wow, you've got some big veins there.
0:28:13 > 0:28:18Obviously a very oxygenated young man!
0:28:18 > 0:28:21Yeah, brilliant! I think I might take this home with me.
0:28:21 > 0:28:25Is that all right? Thank you very much. That is fantastic.
0:28:25 > 0:28:27Would you like to go and sit down?
0:28:31 > 0:28:34So we've been looking at blood in our veins.
0:28:34 > 0:28:39Now let's see haemoglobin for real. This is a tube of pure haemoglobin.
0:28:39 > 0:28:41It looks a bit brown and muddy, doesn't it?
0:28:41 > 0:28:44That's because this is haemoglobin that doesn't contain
0:28:44 > 0:28:47very much oxygen. It's not bound to oxygen very well.
0:28:47 > 0:28:49In fact, in the body we would call it methaemoglobin.
0:28:49 > 0:28:52And if you have too much of this kind of haemoglobin in your body
0:28:52 > 0:28:56that's not good news, because you're not getting enough oxygen.
0:28:56 > 0:29:00But what we can do in this experiment is oxygenate the haemoglobin.
0:29:00 > 0:29:06So Sarah is going to bubble some oxygen through the haemoglobin.
0:29:06 > 0:29:07We're going to get some bubbles, and what's happening here?
0:29:07 > 0:29:09We're going to get some bubbles, and what's happening here?
0:29:09 > 0:29:11Can anyone see a difference?
0:29:11 > 0:29:14I've got a torch here to show the camera.
0:29:14 > 0:29:17Can we see a colour difference there?
0:29:17 > 0:29:19Yeah, quite impressive, isn't it?
0:29:19 > 0:29:22It goes bright red and looks much more like blood.
0:29:22 > 0:29:25So this is haemoglobin containing oxygen
0:29:25 > 0:29:30and this is haemoglobin that isn't bound to very much oxygen.
0:29:30 > 0:29:34And in us, that difference in that protein can be
0:29:34 > 0:29:38the difference between life and death. Thank you very much, Sarah.
0:29:38 > 0:29:40That's fantastic.
0:29:40 > 0:29:43So haemoglobin makes up about 97% of the dry weight
0:29:43 > 0:29:46of our red blood cells.
0:29:46 > 0:29:50And so you can imagine how good an oxygen transporter our red blood
0:29:50 > 0:29:53cells are, because they contain all this haemoglobin.
0:29:53 > 0:29:58So this is a protein inside yourselves in action in you, now.
0:29:58 > 0:30:00So, now we know that all our different tissues
0:30:00 > 0:30:02and organs look and behave differently
0:30:02 > 0:30:05because they're all composed of different cells,
0:30:05 > 0:30:07and cell types can look and behave differently because
0:30:07 > 0:30:11they contain different proteins, and proteins look and behave differently
0:30:11 > 0:30:14because they're made of different combinations of amino acids.
0:30:14 > 0:30:17So we've explained everything, haven't we?
0:30:17 > 0:30:19Or have we?
0:30:19 > 0:30:24What exactly is making all these different amino acids,
0:30:24 > 0:30:27which in turn are making all the different proteins?
0:30:27 > 0:30:31It turns out that the answer lies deep inside
0:30:31 > 0:30:33each and every one of our cells,
0:30:33 > 0:30:37and we're going to have to delve in very deep to find the answer.
0:30:37 > 0:30:40We've looked at quite a few cells now, haven't we?
0:30:40 > 0:30:46But what exactly is inside them? Let's take a look inside a cell.
0:30:46 > 0:30:49So what we've got here is the cytoplasm,
0:30:49 > 0:30:52which is jelly-like stuff, which contains bits and bobs,
0:30:52 > 0:30:55like the mitochondria, which are the little pink things.
0:30:55 > 0:30:57And they make energy in our cells.
0:30:57 > 0:31:00And we've got the golgi apparatus, which are the little yellow
0:31:00 > 0:31:05things, and they help to transport and sort proteins around the cell.
0:31:05 > 0:31:06But look here in the middle.
0:31:06 > 0:31:10In the middle is the nucleus, that's the blue bit.
0:31:10 > 0:31:13The nucleus, the hub of the cell.
0:31:13 > 0:31:18And the nucleus contains a very special substance indeed.
0:31:20 > 0:31:23It was over 140 years ago, in 1869,
0:31:23 > 0:31:27when a Swiss biochemist called Friedrich Miescher...
0:31:27 > 0:31:29There's a picture of Miescher.
0:31:29 > 0:31:33He extracted a substance from the nuclei of white blood cells.
0:31:33 > 0:31:36Scientists had just discovered that cells were the basic unit of
0:31:36 > 0:31:38life and Miescher was desperate to find out
0:31:38 > 0:31:40about their chemical components.
0:31:41 > 0:31:41about their chemical components.
0:31:41 > 0:31:44So do you know how he got hold of his white blood cells? Ugh!
0:31:44 > 0:31:47Do you know how he got his white blood cells?
0:31:47 > 0:31:49Well, every morning, he went to the clinic
0:31:49 > 0:31:51and picked up a load of these.
0:31:51 > 0:31:55Because in the days before antiseptics...
0:31:57 > 0:31:59..these were soaked in pus.
0:31:59 > 0:32:02They really are pussy, aren't they? Ugh!
0:32:02 > 0:32:03These were soaked in pus
0:32:03 > 0:32:06and pus is a good source of white blood cells,
0:32:06 > 0:32:10with their large nuclei, and these were the cells that Miescher wanted,
0:32:10 > 0:32:14because he wanted to get in and find out what was in their nuclei.
0:32:14 > 0:32:16Thank you, Clarissa.
0:32:16 > 0:32:19So, Miescher added alkali to burst open the cells
0:32:19 > 0:32:23and then he extracted a substance that he called nuclein.
0:32:23 > 0:32:26And Miescher got really excited about nuclein because it was
0:32:26 > 0:32:29unlike other biological molecules he'd come across.
0:32:29 > 0:32:33It was an acid and it contained phosphorus.
0:32:33 > 0:32:36Now, this was the first extraction of DNA, of course.
0:32:36 > 0:32:43Nuclein turned out to be deoxyribonucleic acid, or DNA.
0:32:43 > 0:32:47The most important molecule in the living world.
0:32:47 > 0:32:52And the study of DNA is one of the greatest triumphs of modern science.
0:32:52 > 0:32:57It's found in every living thing on earth. But what does it look like?
0:32:57 > 0:32:59Well, let's make some.
0:32:59 > 0:33:03So, Hayley here has been beavering away, making a sample for us
0:33:03 > 0:33:06from some fish roe, so eggs, basically.
0:33:06 > 0:33:08And this sample prep is halfway through
0:33:08 > 0:33:10and she's going to finish it up now,
0:33:10 > 0:33:15she's going to pour on the final solution and we should get some
0:33:15 > 0:33:19nice, stringy DNA,
0:33:19 > 0:33:22which I should be able to spool up
0:33:22 > 0:33:23onto my forceps.
0:33:23 > 0:33:26Let's see this...
0:33:26 > 0:33:29Wow, it's very gloopy. Look at that!
0:33:29 > 0:33:34Can you see these tiny threads of DNA in all this gloop?
0:33:34 > 0:33:38Look at all this stuff! That's amazing.
0:33:38 > 0:33:40Thank you very much, Hayley.
0:33:40 > 0:33:45Thank you for showing us the stuff of life.
0:33:45 > 0:33:48Now, let's fast forward from Miescher in 1869 -
0:33:48 > 0:33:51when Miescher had first done the experiment
0:33:51 > 0:33:53that we've just done - to the 1950s,
0:33:53 > 0:33:55when techniques for determining
0:33:55 > 0:33:59the structure of biological molecules were being developed.
0:33:59 > 0:34:03James Watson and Francis Crick, working in Cambridge,
0:34:03 > 0:34:07capitalised on the newly available data and expertise
0:34:07 > 0:34:12and published the model of the DNA molecule that we know today.
0:34:12 > 0:34:18And here is our very own Royal Institution version of this model.
0:34:18 > 0:34:23One long molecule spiralling around in a double helix.
0:34:23 > 0:34:28Exquisite, ordered, simple and regular.
0:34:28 > 0:34:31Two strands of nucleotides,
0:34:31 > 0:34:35each with a strong backbone composed of sugar and phosphates,
0:34:35 > 0:34:41with what we call nucleotide bases on the inside.
0:34:41 > 0:34:43Adenine - A,
0:34:43 > 0:34:46guanine, or G,
0:34:46 > 0:34:48cytosine - C,
0:34:48 > 0:34:51and thiamine, or T.
0:34:51 > 0:34:54And these bases always pair together according to some
0:34:54 > 0:34:58simple rules. A always pairs with T
0:34:58 > 0:35:01and C always pairs with G.
0:35:01 > 0:35:08These four bases make up an alphabet of four letters, the genetic code.
0:35:08 > 0:35:10And that is the key.
0:35:10 > 0:35:14DNA is a code, a code that holds all the information
0:35:14 > 0:35:16to make all living things.
0:35:16 > 0:35:21An instruction manual to make a worm or a cat or a fly
0:35:21 > 0:35:24or a human or a dinosaur.
0:35:24 > 0:35:29Its regularity, stability, reliability and predictability,
0:35:29 > 0:35:35even its relative boringness, make it the perfect system for storing
0:35:35 > 0:35:40the vast amount of information necessary for building life.
0:35:40 > 0:35:42Somehow, DNA must tell
0:35:42 > 0:35:47each and every cell in the body what it is to become and when and where.
0:35:49 > 0:35:54But how? 1950s scientists had a big job to do.
0:35:54 > 0:35:57They had to crack the code.
0:35:57 > 0:36:00So if you consider how a code works, let's think it out.
0:36:00 > 0:36:02We've got four bases
0:36:02 > 0:36:05and we know that we need to make 20 different amino acids.
0:36:05 > 0:36:09So if we have a code that just consists of one base,
0:36:09 > 0:36:13we could only make four possible amino acids, right?
0:36:13 > 0:36:15Which isn't enough.
0:36:15 > 0:36:19So if we had a code that consisted of two bases that could get
0:36:19 > 0:36:21together in any combination,
0:36:21 > 0:36:24how many different amino acids could we make then?
0:36:24 > 0:36:27Yes? 16, exactly.
0:36:27 > 0:36:30Not enough, is it? We need 20.
0:36:30 > 0:36:34So if we had a code based on three bases that could get together
0:36:34 > 0:36:39in any combination, how many amino acids could we produce then?
0:36:39 > 0:36:42Nine? Not quite.
0:36:42 > 0:36:4864! Exactly! More than nine and more than we need.
0:36:48 > 0:36:52So, three bases would work.
0:36:52 > 0:36:56And that's exactly what scientists found to be the case.
0:36:56 > 0:37:00They worked out the code and they worked out that it was arranged in
0:37:00 > 0:37:03threes - a triplet code,
0:37:03 > 0:37:07with each group of three bases called a codon.
0:37:07 > 0:37:11And each group of three bases, or codon, specifies - or codes -
0:37:11 > 0:37:15for a particular amino acid. So we can see that here.
0:37:15 > 0:37:21Here's a codon of three bases and that will give us
0:37:21 > 0:37:25an amino acid, which we give another single letter code to.
0:37:25 > 0:37:28We needn't worry about the amino acid codes for now.
0:37:28 > 0:37:33So here's another codon - CCC - that gives us this amino acid, P.
0:37:33 > 0:37:40And here's another codon - GAA - that gives us that amino acid E.
0:37:40 > 0:37:43So we can start to decode this DNA sequence
0:37:43 > 0:37:46and turn it into an amino acid sequence.
0:37:46 > 0:37:52So we can see a growing amino acid chain in a protein.
0:37:52 > 0:37:56I'm not going to waste my time decoding all of that now.
0:37:56 > 0:38:00We've got one here that we prepared earlier. We know it's the same.
0:38:00 > 0:38:04This is all these nucleotides, all these codons,
0:38:04 > 0:38:09decoded into these amino acids. So here is our protein chain.
0:38:09 > 0:38:14So a protein is like a sentence of amino acid letters.
0:38:14 > 0:38:17And you can see that we've got punctuation in our sentences,
0:38:17 > 0:38:20because it turns out that there are special codons that make
0:38:20 > 0:38:24something like a full stop at the end of the protein.
0:38:24 > 0:38:28Now, the question is, can we find some useful sentences in this
0:38:28 > 0:38:32string of sequences that might represent useful proteins?
0:38:32 > 0:38:34Can I have a volunteer to help me out here?
0:38:34 > 0:38:36Let's have you on the end there. Thank you very much.
0:38:36 > 0:38:38Let's have you on the end there. Thank you very much.
0:38:38 > 0:38:41What's your name? Kirsty.
0:38:41 > 0:38:43Right, Kirsty, if you'd like to come over here.
0:38:43 > 0:38:47I want you to play a sort of wordsearch game, OK?
0:38:47 > 0:38:49It's a very simple wordsearch,
0:38:49 > 0:38:53nothing diagonally or backwards or any of those hard things.
0:38:53 > 0:38:56It's just going to be a sentence going across like you would read a book.
0:38:56 > 0:38:59Have a look at these letters
0:38:59 > 0:39:02and see if you can pick out an actual sentence that might make sense.
0:39:04 > 0:39:06Let's have a look...
0:39:06 > 0:39:07What have we got?
0:39:09 > 0:39:11"Make a..." "Make a liver...
0:39:11 > 0:39:15"Make a liver cell." "Make a liver cell."
0:39:15 > 0:39:19That sounds quite good, doesn't it? Have we got any more there?
0:39:19 > 0:39:21Let's highlight that one, shall we?
0:39:21 > 0:39:23"Make a liver cell." Have we got any more here?
0:39:23 > 0:39:26"Make a heart cell." You're very quick at this!
0:39:26 > 0:39:30Have you seen this before? No. Let's highlight that one.
0:39:30 > 0:39:34So you've done something very clever here, you've found two genes.
0:39:34 > 0:39:39So the first gene is making our protein called "make a liver cell"
0:39:39 > 0:39:42and the second gene is making our protein called "make a heart cell".
0:39:42 > 0:39:46What you think the "make a liver cell" protein
0:39:46 > 0:39:49might be doing in the body?
0:39:49 > 0:39:51Making a liver. Making a liver, absolutely.
0:39:51 > 0:39:54And what do you think the "make a heart cell" protein might be doing?
0:39:54 > 0:39:58Making a heart. That sounds pretty useful, doesn't it?
0:39:58 > 0:40:01Kirsty, thank you so much for showing us the way.
0:40:03 > 0:40:05So that's it.
0:40:05 > 0:40:07Different proteins are made in different cells,
0:40:07 > 0:40:10so that cells can look and behave differently from one another,
0:40:10 > 0:40:15to make complicated things like worms and us, because of the DNA.
0:40:16 > 0:40:18Hang on a minute...
0:40:18 > 0:40:21If we go back to our worm, our worms been very busy
0:40:21 > 0:40:23while we haven't been looking at.
0:40:23 > 0:40:27Pete's been keeping score there and we've now have five cell divisions.
0:40:27 > 0:40:28It's been very busy.
0:40:28 > 0:40:34But we've seen that all these cells have come from this first cell.
0:40:34 > 0:40:37So all these cells will contain exactly the same DNA
0:40:37 > 0:40:41because DNA is duplicated each time a cell divides.
0:40:42 > 0:40:45So now we've got ourselves a problem, haven't we?
0:40:45 > 0:40:49All of our cells, no matter what their role is,
0:40:49 > 0:40:52contain exactly the same DNA.
0:40:52 > 0:40:54It's the same for any organism.
0:40:54 > 0:40:59Each species is defined by its complete DNA system, it's genome.
0:40:59 > 0:41:02So what on earth is going on? How does this work?
0:41:02 > 0:41:06How do cells in us become different from one another?
0:41:06 > 0:41:06And we've seen how different they can become.
0:41:06 > 0:41:08And we've seen how different they can become.
0:41:08 > 0:41:12But how do they do this if they contain the same DNA?
0:41:12 > 0:41:14So, to find out,
0:41:14 > 0:41:18scientists had to have another look at the code in even more depth.
0:41:18 > 0:41:20And it turns out that there's more to genes than just
0:41:20 > 0:41:26strings of codons. So let's have a look at our word search game again.
0:41:26 > 0:41:30What did Sarah do to light up the sentence?
0:41:30 > 0:41:31Let's go round the back here.
0:41:31 > 0:41:35Sarah, what did you do to switch, to highlight these proteins?
0:41:35 > 0:41:37I just pushed a switch.
0:41:37 > 0:41:43So do it again. Off, on. Off...on.
0:41:43 > 0:41:47You flicked a switch. Sarah flicked a switch.
0:41:47 > 0:41:52And that's exactly what happens in a cell.
0:41:52 > 0:41:55Genes can be switched on and off.
0:41:55 > 0:41:59They can make a protein or not.
0:41:59 > 0:42:01If they make a heart cell protein, it's going to be
0:42:01 > 0:42:05switched on in our heart cells but off in our liver cells.
0:42:05 > 0:42:09So we say the "make a heart cell" gene is EXPRESSED in our heart cells
0:42:09 > 0:42:12and not expressed in our liver cells.
0:42:12 > 0:42:16And that makes sense, because if your "make a heart cell" gene was expressed in your
0:42:16 > 0:42:19liver cells and you made the "make a heart cell" protein in your liver cells,
0:42:19 > 0:42:21your liver cells might start beating.
0:42:21 > 0:42:25Do think that would be a good idea? No, neither do I.
0:42:25 > 0:42:28So, understanding this problem of gene expression
0:42:28 > 0:42:34is one of the key goals of molecular biology, even today.
0:42:34 > 0:42:40So can we see this gene expression thing for real, in a real animal?
0:42:40 > 0:42:41Oh, yes, we certainly can.
0:42:41 > 0:42:43But curiously enough,
0:42:43 > 0:42:46we need a little help from a glow-in-the-dark jellyfish.
0:42:48 > 0:42:52And here's a picture of our jellyfish. Isn't it lovely?
0:42:52 > 0:42:55This jellyfish is called Aequorea victoria
0:42:55 > 0:42:59and it has a very special property, because when you shine blue light
0:42:59 > 0:43:04on the jellyfish, like we are here, they glow green.
0:43:04 > 0:43:07And they glow green because they produce a protein called GFP,
0:43:07 > 0:43:09green fluorescent protein.
0:43:09 > 0:43:11Not very imaginative, but it tells you what it does.
0:43:11 > 0:43:14Green fluorescent protein.
0:43:14 > 0:43:18So, the green fluorescent protein is produced by the GFP gene
0:43:18 > 0:43:21when the gene is switched on.
0:43:21 > 0:43:24And the glowing thing is really useful for scientists
0:43:24 > 0:43:26because we can see it.
0:43:26 > 0:43:28It's a biosensor.
0:43:28 > 0:43:32But how does that help us understand the problem of gene expression?
0:43:32 > 0:43:38Well...we can copy the GFP gene out of the jellyfish genome
0:43:38 > 0:43:44and paste it into any gene in any cell in pretty much any organism.
0:43:44 > 0:43:48The fluorescent protein will become incorporated into whatever protein
0:43:48 > 0:43:52that gene normally produces, which will also glow.
0:43:52 > 0:43:56So we know when a gene is switched on.
0:43:56 > 0:43:56We know where it's switched on in what cells and at what time.
0:43:56 > 0:44:00We know where it's switched on in what cells and at what time.
0:44:00 > 0:44:04If the cell is green, then that means the gene is on.
0:44:04 > 0:44:08I'm going to show you some very special worms again.
0:44:10 > 0:44:12So here are some worms,
0:44:12 > 0:44:15cruising around on their plate looking very normal.
0:44:15 > 0:44:19But what Pete has done here, is to insert the GFP gene
0:44:19 > 0:44:26into a gene that is only expressed - or switched on - in muscle cells.
0:44:26 > 0:44:29It produces a kind of "make a muscle cell" protein, and that's
0:44:29 > 0:44:32part of the reason why these worms wriggle like a worm should.
0:44:32 > 0:44:35If we shine blue light on the worm,
0:44:35 > 0:44:42which Peter is going to do now, then what we'll see are green spots.
0:44:43 > 0:44:45Isn't that beautiful?
0:44:45 > 0:44:48They are glow-in-the-dark worms.
0:44:48 > 0:44:51The GFP, the green fluorescent protein, is showing us
0:44:51 > 0:44:54the muscle cells of the worm and no others,
0:44:54 > 0:44:57because this gene is switched on in muscle cells.
0:44:57 > 0:45:01And we can see that the worms have two rows of these muscle cells
0:45:01 > 0:45:04along each side of their bodies.
0:45:04 > 0:45:07And they contract in a very co-ordinated way to help this
0:45:07 > 0:45:10worm have this very elegant movement.
0:45:10 > 0:45:13So it's the switching on of this gene in these cells,
0:45:13 > 0:45:17and only these cells, during the development of the animal,
0:45:17 > 0:45:22that makes the cells look and behave like muscle cells.
0:45:22 > 0:45:26And this ultimately enables the animal to wriggle around.
0:45:26 > 0:45:30So we've used GFP to track exactly when this gene is switched on.
0:45:31 > 0:45:35Pete, thank you, your work here is done.
0:45:35 > 0:45:36Ladies and gentlemen, Pete Appleford!
0:45:36 > 0:45:37Ladies and gentlemen, Pete Appleford!
0:45:37 > 0:45:39APPLAUSE
0:45:39 > 0:45:43Next question. And I can see you're thinking this too.
0:45:43 > 0:45:45How on earth do these switches work?
0:45:47 > 0:45:52In the cell, what is the finger, the finger like Sarah's finger,
0:45:52 > 0:45:55that presses the switch to turn the gene on?
0:45:55 > 0:45:58Well, the answer is it's a protein.
0:45:58 > 0:46:00A regulatory protein.
0:46:00 > 0:46:05And I've got a model here to show you how this works.
0:46:05 > 0:46:09If I can actually get it out of the box...
0:46:09 > 0:46:12We've got a DNA molecule here.
0:46:14 > 0:46:18This is the DNA and here is our regulatory protein.
0:46:18 > 0:46:21And what that's going to do is bind to the DNA...
0:46:21 > 0:46:23It sticks to it like glue.
0:46:23 > 0:46:26It's binding to this DNA
0:46:26 > 0:46:31and it's that act of binding to the DNA that is switching a gene on.
0:46:31 > 0:46:32So, regulatory proteins are the things in cells
0:46:32 > 0:46:35So, regulatory proteins are the things in cells
0:46:35 > 0:46:37that switch genes on.
0:46:37 > 0:46:39That's all well and good, isn't it?
0:46:39 > 0:46:42But hang on a minute...
0:46:42 > 0:46:46If this regulatory protein is the thing that is switching
0:46:46 > 0:46:50this gene on, where did that regulatory protein come from?
0:46:50 > 0:46:53Well, it's coded by the DNA, because all proteins are.
0:46:53 > 0:46:59So it must be switched on by another regulatory protein.
0:46:59 > 0:47:01So where does that regulatory protein come from?
0:47:01 > 0:47:01So where does that regulatory protein come from?
0:47:01 > 0:47:04Well, that regulatory protein must be coded for by DNA,
0:47:04 > 0:47:05because all proteins are.
0:47:05 > 0:47:08So that regulatory protein must be switched on by...
0:47:09 > 0:47:12..another regulatory protein.
0:47:12 > 0:47:16Complicated, isn't it? Where does it all start?
0:47:16 > 0:47:20And that's what scientists are still grappling with today.
0:47:20 > 0:47:20So, we've come a long way, but how on earth do we know all this?
0:47:21 > 0:47:22So, we've come a long way, but how on earth do we know all this?
0:47:22 > 0:47:26So, we've come a long way, but how on earth do we know all this?
0:47:26 > 0:47:30How do we know which gene does which job? Which are the heart genes?
0:47:30 > 0:47:32Which gene is the liver gene?
0:47:32 > 0:47:36Which gene controls the very first cell division?
0:47:36 > 0:47:40In fact, how does a cell know where its middle is anyway?
0:47:40 > 0:47:46How do we work it all out? How do we work out which gene does which job?
0:47:46 > 0:47:49Well, it may sound surprising, but what geneticists do
0:47:49 > 0:47:52when they want to study a particular biological process,
0:47:52 > 0:47:56is they look when it goes wrong because of a defect in a gene.
0:47:56 > 0:48:02A mutation. OK, I've said mutation now. What do I mean?
0:48:04 > 0:48:07A mutation is a change in a DNA sequence.
0:48:07 > 0:48:11So the change in a DNA sequence can have big consequences.
0:48:11 > 0:48:13Look at this one, for examples.
0:48:14 > 0:48:14Look at this one, for examples.
0:48:14 > 0:48:17This codon here, GAA,
0:48:17 > 0:48:21has changed in this codon to GGA.
0:48:21 > 0:48:24You're thinking that's not such a big deal, is it?
0:48:24 > 0:48:28That's only one nucleotide in a string of DNA.
0:48:28 > 0:48:33What's going to happen to the protein that this sequence produces?
0:48:33 > 0:48:34Let's take a look.
0:48:36 > 0:48:41This altered codon is going to give us the amino acid G.
0:48:41 > 0:48:45And the amino acid G is going to go in place of the amino acid
0:48:45 > 0:48:48that should have been produced here, called E.
0:48:48 > 0:48:53So if we highlight our "make a heart cell" gene again, what happens?
0:48:53 > 0:48:55There's a mistake. What does it say now?
0:48:57 > 0:49:01Make a what? Make a hgart cell.
0:49:01 > 0:49:04Does that sound like it's going to do the job?
0:49:04 > 0:49:05ALL: No. It doesn't.
0:49:05 > 0:49:08That does not sound like it's going to do the job and make the heart.
0:49:08 > 0:49:13So you can now see the consequence of a mutation in a DNA sequence.
0:49:13 > 0:49:16In this case, we are going to end up with heart cells that don't
0:49:16 > 0:49:20actually do their job, so that would be our mutant animal.
0:49:20 > 0:49:23Our mutant animal would have a dodgy heart.
0:49:23 > 0:49:26Right, shall we meet some real live mutants now?
0:49:26 > 0:49:32So, time to meet another one of our hero model organisms.
0:49:32 > 0:49:36Now, it's not worms this time, it's something else.
0:49:36 > 0:49:41Does anyone know what is in this box of rotten bananas? Yes?
0:49:41 > 0:49:42Maggots?
0:49:42 > 0:49:46Well, probably a few but there's other things in there as well.
0:49:46 > 0:49:50Yes? Flies. Flies. They're very nice, aren't they?
0:49:50 > 0:49:54This is the fruit fly, Drosophila melanogaster.
0:49:54 > 0:49:56Another one of our hero model organisms that has
0:49:56 > 0:49:59so much to teach us about biology,
0:49:59 > 0:50:03and in particular developmental biology.
0:50:03 > 0:50:07Some of the flies in this box actually have a few issues.
0:50:07 > 0:50:09We've got some mutant flies in this box.
0:50:09 > 0:50:12But they're very small, so we need to look at them
0:50:12 > 0:50:16under a microscope to see what they really would look like.
0:50:16 > 0:50:20So our first picture is going to be a normal fly.
0:50:20 > 0:50:22This is the head of a fly.
0:50:22 > 0:50:25You can see its very beautiful eyes, made of all these ommatidia
0:50:25 > 0:50:27on each side of the head.
0:50:27 > 0:50:30And then we've got the antennae sticking out as they normally would.
0:50:30 > 0:50:34So everything is present and correct in this fly. It's a happy fly.
0:50:34 > 0:50:37It's flying around in our box of bananas very happily.
0:50:37 > 0:50:41But the next fly has something wrong with it.
0:50:41 > 0:50:44The normal one is on the left and the mutant on the right.
0:50:44 > 0:50:46Can anyone spot the difference?
0:50:46 > 0:50:47Yes, what do you think, Ollie?
0:50:47 > 0:50:49It has legs growing out of its face.
0:50:49 > 0:50:53It's got legs growing out of its face.
0:50:53 > 0:50:55I wouldn't like it if that happened to me!
0:50:56 > 0:50:59So, this is something very wrong.
0:50:59 > 0:51:03It's got legs instead of antennae.
0:51:03 > 0:51:05I think that is a big thing to get wrong.
0:51:06 > 0:51:13And this problem is caused by a single mutation in a single gene.
0:51:13 > 0:51:16So when this protein doesn't work properly, the wrong switches
0:51:16 > 0:51:20are flicked and hey presto, you've got legs sprouting from your head.
0:51:20 > 0:51:21Nasty.
0:51:21 > 0:51:23Now, the really important point here, though,
0:51:23 > 0:51:29is that these mutant flies reveal what we call a "how do we know this?" moment.
0:51:29 > 0:51:31We know that this gene,
0:51:31 > 0:51:35the gene that's gone wrong in these mutants, must be absolutely
0:51:35 > 0:51:41crucial for putting antennae in the right place, and not legs.
0:51:41 > 0:51:44And when it goes wrong, you can see what happens.
0:51:44 > 0:51:48So we start with the mutant. That's the approach.
0:51:48 > 0:51:52And then we work out which gene has gone wrong and that tells us
0:51:52 > 0:51:55which gene normally makes this process go right.
0:51:55 > 0:52:00So, mutants are extremely useful. They reveal how processes work.
0:52:00 > 0:52:04And in the lab, we use special chemicals that increase
0:52:04 > 0:52:08the chances of mutations occurring in the DNA of the organism
0:52:08 > 0:52:11and then we look through loads of mutants until we find a fascinating
0:52:11 > 0:52:15one, like a fly with legs instead of antennae, and we use that
0:52:15 > 0:52:19as a way of finding what the gene is that normally makes that go right.
0:52:19 > 0:52:21So this is the genetic approach.
0:52:21 > 0:52:25Studying mutants opens a dialogue with the organism about what genes
0:52:25 > 0:52:28are the most important for a particular process.
0:52:28 > 0:52:32We can ask pretty much any question about biology in this way.
0:52:32 > 0:52:34It's incredibly powerful.
0:52:34 > 0:52:38Some people call it the "awesome power of genetics".
0:52:38 > 0:52:41And now I'm going to introduce you to someone who
0:52:41 > 0:52:42is particularly good at it.
0:52:42 > 0:52:47Goodness me! Good heavens! It's Paul Nurse! Hello, Alison. Welcome!
0:52:47 > 0:52:49Lovely to see you.
0:52:51 > 0:52:54What's the deal with the bike? It's a terrible bike. It is.
0:52:54 > 0:52:57There should be handlebars there but there's pedals.
0:52:57 > 0:52:59Something wrong with the instructions.
0:52:59 > 0:53:02It's just like the fly you're all looking at. Yeah.
0:53:02 > 0:53:06Pedals instead of handlebars. There's something else wrong with this bike.
0:53:06 > 0:53:11What else? It's dangerous - it's got no bell. No bell?
0:53:11 > 0:53:14But I understand you got a Nobel Prize.
0:53:14 > 0:53:16LAUGHTER
0:53:16 > 0:53:19That was a very bad joke, Alison. I know, I couldn't resist.
0:53:19 > 0:53:21Perhaps you'd like to stay to tell us
0:53:21 > 0:53:24something about how you got your Nobel Prize.
0:53:24 > 0:53:29I was interested in yeast, and in my pocket I have some growing yeast.
0:53:29 > 0:53:32How many of them are there on the plate.
0:53:32 > 0:53:34Each of these pink blobs
0:53:34 > 0:53:38has got about 10 million to 100 million cells.
0:53:38 > 0:53:40So they're really small. Very, very small.
0:53:40 > 0:53:45Ten micrometres, much smaller than flies. Much smaller than worms.
0:53:45 > 0:53:47Let's have a look at them under the microscope.
0:53:47 > 0:53:52I think you have some under there, don't you? I hope so. Oh, look!
0:53:52 > 0:53:56That's what I devoted 40 years of my life looking at.
0:53:56 > 0:53:57LAUGHTER
0:53:57 > 0:54:01And are they dividing? These are fission yeast.
0:54:01 > 0:54:05They're like little sausages and they grow longer and longer,
0:54:05 > 0:54:08and when they get to a certain length, they divide into two
0:54:08 > 0:54:12and then into four, and then into eight, just as we saw earlier.
0:54:12 > 0:54:14And you spent 40 years studying that process.
0:54:14 > 0:54:17I'm a very sad person, Alison.
0:54:17 > 0:54:19So, how did you do it?
0:54:19 > 0:54:20Well, me and my colleagues,
0:54:20 > 0:54:24including yourself at the time, we looked for mutants,
0:54:24 > 0:54:29and we looked for mutants that were defective in genes that were
0:54:29 > 0:54:31important for cell division.
0:54:31 > 0:54:35Now, imagine what would happen if you could grow but you couldn't divide.
0:54:35 > 0:54:38What would happen is that those sausages would get longer
0:54:38 > 0:54:41and longer and longer.
0:54:41 > 0:54:44And so if you look down the microscope, that's what you'd see.
0:54:44 > 0:54:47So this is a cell division control mutant.
0:54:47 > 0:54:52This is a cell that contains a gene that is defective in completing
0:54:52 > 0:54:53the cell cycle. It can't do it. There must be lots of these genes.
0:54:53 > 0:54:56the cell cycle. It can't do it. There must be lots of these genes.
0:54:56 > 0:55:01We now know - we didn't at the time - there's about 300 genes in this
0:55:01 > 0:55:06yeast that are important for controlling its division. Wow. Lots of genes.
0:55:06 > 0:55:10But amongst them there's one or two that are much more important.
0:55:10 > 0:55:14These are the ones that tell the cell whether to divide or not.
0:55:14 > 0:55:18And these are the ones that tell the cell how fast they should divide.
0:55:18 > 0:55:21It's rather like the accelerator in a car.
0:55:21 > 0:55:22There's many bits to a car,
0:55:22 > 0:55:27but if you want to control how fast it goes you work on the accelerator.
0:55:27 > 0:55:29So that tells us an awful lot about the yeast and,
0:55:29 > 0:55:33no disrespect, you know an awful lot about yeast.
0:55:33 > 0:55:36What does that tell us about other organisms?
0:55:36 > 0:55:38You're right, I am very interested in yeast,
0:55:38 > 0:55:42but I don't think the rest of the world is. I think these guys are.
0:55:42 > 0:55:45But we are very interested in ourselves. Oh, yes.
0:55:45 > 0:55:50So the question is, do the genes that control the division of this yeast
0:55:50 > 0:55:55also control the division of all the cells in us?
0:55:55 > 0:55:56How do you find out?
0:55:56 > 0:55:58Well, you can look to see
0:55:58 > 0:56:02if there is a gene the same as the gene here in humans.
0:56:02 > 0:56:04How do you do that?
0:56:04 > 0:56:07Well, it's difficult, because the last common ancestor
0:56:07 > 0:56:13between yeast and ourselves was probably 1.5 billion years ago.
0:56:13 > 0:56:16So we are nothing like yeast. Nothing like yeast.
0:56:16 > 0:56:22And to put that in context, dinosaurs went extinct 65 million years ago.
0:56:22 > 0:56:25That's just a flash in time. It's 20 times older.
0:56:25 > 0:56:30So this is a difficult project. So what did we do? What we did,
0:56:30 > 0:56:34and it was done by somebody in my lab called Melanie Lee,
0:56:34 > 0:56:36and she took human DNA, chopped it up into pieces
0:56:36 > 0:56:41and then sprinkled it on to the defective yeast cells.
0:56:41 > 0:56:43And the idea was that
0:56:43 > 0:56:47if there was a human gene that did the same job as the gene
0:56:47 > 0:56:51that's defective here, if the yeast took it up,
0:56:51 > 0:56:57then it could substitute the defective yeast gene.
0:56:57 > 0:57:00So it would rescue those mutants? It would rescue that defect.
0:57:00 > 0:57:05And the genes were almost exactly the same.
0:57:05 > 0:57:10Despite the 1.5 billion years, they were almost exactly the same.
0:57:10 > 0:57:13So when we find that out, then we can start to think about
0:57:13 > 0:57:15how this might help us in medicine, right?
0:57:15 > 0:57:19We do, because what it tells us is the way in which yeast cells
0:57:19 > 0:57:22control their division is actually exactly the same way
0:57:22 > 0:57:25as how we control our cell division.
0:57:25 > 0:57:27Which can sometimes go wrong.
0:57:27 > 0:57:30Which can go wrong, and when it goes wrong we get disease.
0:57:30 > 0:57:32The most common one that goes wrong is cancer.
0:57:32 > 0:57:36And what causes it is activation eventually of these genes
0:57:36 > 0:57:38that cause cell division.
0:57:38 > 0:57:40So working on yeast can even help us in cancer research.
0:57:40 > 0:57:45It can. If we want to think about new ways of treating cancer, new therapies,
0:57:45 > 0:57:50we have to understand what's going on during the cell division process
0:57:50 > 0:57:53and we can work it out much more quickly working on yeast
0:57:53 > 0:57:56than we can on human cells. Paul, that's amazing.
0:57:56 > 0:58:00Ladies and gentlemen, Nobel Prize winner Paul Nurse.
0:58:00 > 0:58:01Thank you!
0:58:05 > 0:58:08So...this has been quite a journey, hasn't it?
0:58:08 > 0:58:14Isn't it extraordinary how organisms develop from a single cell?
0:58:14 > 0:58:18How those cells know what to do and how it's all written in the genes.
0:58:18 > 0:58:21Next time we'll see how the developmental programmes
0:58:21 > 0:58:26we discovered today can vary over time, and understand how this is at
0:58:26 > 0:58:32the very heart of evolution and the diversity of our fantastic planet.
0:58:32 > 0:58:33Thank you and good night.