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The Cell - The Hidden Kingdom (Part 4/6)

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And he was the first to describe it properly, give it the name, 'the nucleus', and show how ubiquitous it was. And after he'd seen the nucleus for the first time, what was his interpretation of what he was looking at? Well, he obviously didn't understand the role of the nucleus, as we would understand it today, but the important thing was, that he said these are in all cells, because he started looking at other plants & other plants & other plants & other plants and then he found that they were everywhere, and therefore the idea that each cell has one nucleus comes from his work, 1830.

The identification of the nucleus wasn't Robert Brown's only contribution to science. He's much better known for his role in Physics, where he was looking at the movement of particles within pollen grains, what we now call Brownian motion. A hundred years later, a chap called Albert Einstein would use Brownian motion to prove the existence of the atom. So Brown has a unique position in the history of science, as having made major contributions to atomic theory and to cell theory, the smallest units of matter and the smallest units of life. Respect!

Brown's observation would one day allow us to understand how cells work. Since then we've discovered the nucleus is the control centre that runs each cell. Not only that, but within it are the instructions to make every cell in an organism. In 1831, though, just knowing that the nucleus was there was the breakthrough. Its presence in cells would be the clue to show that the cell might be universal to all living things. Though no one yet could suggest something so radical.

Before biology could progress any further, scientists had to build a much more powerful microscope. But they'd reached a technological impasse. Now, it was an Englishman, Joseph Jackson Lister, who rose to the challenge. He was a wealthy wine merchant, but had been long obsessed with microscopes. So in his spare time, he set about designing one that would be superior to all others. Lister figured that he needed two lenses, unlike the single lens microscopes of Van Leeuwenhoek and Brown. Using two lenses had been tried many times before. It boosted magnification, but it also boosted some of the problems inherent in all lenses. The most vexing of these, was an effect known as colour blurring. You can get a feel for what this looks like by fiddling with the lens on the camera, this weird coloured halo around the edge of the light, that's what I'm talking about. Lister's genius was to discover, that there was one specific distance between two lenses, where colour blurring and other focusing problems were minimised. In 1830, after several years of hard graft, experimenting with different types of lenses, testing out various prototypes, Lister revealed his new design of microscope. For the first time, since Van Leeuwenhoek, there were the means and the know how, to build ever more powerful microscopes. This amateur scientist had made a breakthrough that rendered the single lens microscope obsolete. Now biologists had the tool that allowed them to go deeper and deeper inside the world of the cell.

The stage was set, but what was still lacking were the scientists with the imagination to see cells for what they really were. And here in Berlin one young and ambitious man was about to break the impasse - Theodor Schwann. The 2 strands of biology, animal & vegetable, were about to come together. At the time Berlin was the European centre for anatomy, and the university a magnet for the most brilliant biologists around. Theodor Schwann was keen to make a name for himself and took a position at the prestigious Anatomical Museum. Be warned though, it's not for the faint hearted. The guidebook comments "Boys will be admitted only in the company of their fathers or teachers, and of the female sex, only midwives will be granted admission. The visitors attention is called mainly to the wealth of nerve preparations, a long array of monstrous births and about 500 animal skeletons".

The field of anatomy was in chaos. Nobody really knew what animals or humans were made of. Researchers believed that they were built of many different structures - granules, fibres, tubes, globules and bladders and none of them seemed any more important than the others. Animal studies were seriously lagging behind botany and this was because the cells are so much harder to see. So the scientists didn't really realise there were any cells there at all and this was fuelling the notion that somehow, animal tissue was fundamentally different from that of plants. But Schwann used innovative ways to stain his animal tissue, and he had one of the new Lister style microscopes. He kept finding the same type of globular structures in all the different samples We know that Schwann was looking at cells, but at the time researchers used different terms to describe what they were seeing K├Ârnchen, K├╝gelchen and Zellen. The penny hadn't dropped that they were looking at the same thing and without this connection, they couldn't make the intellectual leap, that cells were common to all life forms.

That was all to change one day in October 1837. Over a meal Schwann was chatting about his work to a fellow scientist, a guy called Matthias Schleiden. Now, Schleiden had also been studying cells, but he'd been looking at plants Schleiden talked passionately with Schwann about his investigation into the makeup of dozens of different plants, from grasses to tulips. In turn, Schwann revealed his work on the nerves of the edible frog. Could such very different things, tulips and frogs, be built of the same microscopic structure? It seemed unlikely in the extreme. The popular perception of scientific discovery is that there's a sudden brainwave and you leap out of the bath everything becomes clear and you run up and down the street in the buff. The sad truth is a little more disappointing. Most scientists toil away, grinding out small incremental advances. However, Schwann and Schleiden's meeting was a classic Eureka moment Up to this point neither knew the other's research but both scientists had been using the nucleus as the way to identify their building blocks This is a typical plant cell - it has a well defined cell wall, and a single nucleus, and this is a typical animal cell - it has a soft boundary, which is difficult to make out, but a cell membrane all the same. It also has a single nucleus. By comparing the two, the scientists knew that they were looking at, essentially, the same thing. They were both cells.

Everything they'd observed was built of cells. Schleiden's flowering plants and grasses, Schwann's frogs and other animal samples. Now they realised, that wherever there was life, there were cells. I believe this is one of the three great concepts in biology. It's right up there with Darwin's theory of evolution and the discovery of the structure of DNA. Schwann and Schleiden had uncovered an idea that united all life on Earth. This meal was where biology changed forever. Animals and plants, humans and amoebas - they were all made of the same building block - cells. In Schwann's book, he explained how cells were self-sufficient units that could work together to make up a much larger organism, a co-operative of cells.

Schwann & Schleiden went down in history as the founders of Cell Theory. At least that's the conventional view. The truth is a bit more complicated and a bit more interesting, I think. You see, Schwann & Schleiden got half of their theory completely wrong and their error sent Biology down blind alley for more than a decade. Their mistake was about where cells actually come from.

Video Details

Duration: 10 minutes and 19 seconds
Country: United Kingdom
Language: English
Producer: BBC Four
Views: 2,288
Posted by: vallisso on Oct 28, 2009

Episode 1 of 3

Dr Adam Rutherford introduces a new three-part series that tells the extraordinary story of the scientific quest to discover the secrets of the cell and of life itself. Every living thing is made of cells, microscopic building blocks of almost unimaginable power and complexity.

The first part explores how centuries of scientific and religious dogma were overturned by the earliest discoveries of the existence of cells, and how scientists came to realise that there was, literally, more to life than meets the eye.

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