[MUSIC] Okay, so you have to imagine these two guys. Francis Crick is in his 30s. He doesn't have PhD yet. Watson, Jim Watson is 23. He has a PhD as a postdoc. He's into his first or second postdoc depending on how you want to count. They decided to play with models and they had, A lot of help. They had help from two people. The most important is Donohue, who they thank in their paper. The other help they had was from Pauling’s son, who was a postdoc in the lab and got them the pre-prints of his father's triple helix model. And they immediately knew that the model was wrong, but it helped them think about it. So basically, they were doing, trying to put models together, and they forgot that DNA is very hydrated. And that DNA has sodium salt around it. And so it had to be hydrated. And then of course, this mistake was compounded by the fact that at one time, both Crick and Watson were supposed to go to London to talk to Rosalind Franklin, but Crick couldn't go, and so Jim went alone. But Jim didn't know anything about crystallography, and so he confused asymmetric units and unit cell, which are two different things in crystallography. And so of course he didn't understand what the other one was talking about. Donohue was critical because he told them what is the arrangement of the atoms in the bases. And the arrangement in the atom is not what was in the textbook at the time. Donohue told them the exact arrangement of atoms in the bases. So in the bases you have to simplify carbon, oxygen, and carbon. These can be linked in two different ways. What is called a keto and of course there is a fourth bond here. And what is called an enol. Which is the C, alcohol, which is basically an alcohol, and a double bond here. You can count the electrons and they are the same. It's a flat structure in both cases. But in one case you have an oxygen with a cloud of electrons here. In this case, you have a little cloud and you have a proton which can be given to an electron. So these structures have very different chemical reactivity, chemical bonding properties, although they look the same and they are, of course here, though they're hydrogen, the number of atoms is the same. So Donohue told them that, in the textbook, that was the structure. And Donohue told them this is real. And that was extremely important. And basically, once they realized that, Watson managed to find the base pairing, namely the A with the T and the G with the C. Watson was supposed to work on the crystallization of myoglobin with Kendrew which he didn't do. So they have something close to a structure, but they are not sure whether it's a real structure. They don't have the two pictures from London and they only have a vague idea of what the pictures are. And they decide nevertheless, that they're going to publish their model, because they believe that what they know about the data from London is compatible with their model and their other data compatible with their model. And so, they decide to go ahead. So you're going to have three papers appear in the same issue, one after each other. So this is a picture that shows Watson and Crick, with a tie on so they look respectable, around a model of DNA, which is close to the kind of model they were using. This has nothing to do with the way they were working. This is a complete reconstruction of what they wanted us to believe reality was. They were not working like that. But that doesn't matter. Okay, so now we're going to go through the paper. Before we go through the paper, remember, Watson and Crick have a model which is a theoretical model. Wilkins has images. Rosalind Franklin has images. Now, Rosalind Franklin is a very tough scientist. She's a very good scientist, but she's tough. And she's tough because she comes from a family where her parents didn't wanted her to do science. She comes from a relatively rich Jewish family and she was supposed to marry a banker or something, not have an independent career. So she had to prove herself or she thought she had to prove herself. In private, she was apparently an extremely nice person. But in the field, or in the lab, she was extremely competitive and quite aggressive. And to the point that people don't realize that, for instance, she managed to get some very pure DNA from a guy in Bern, named Signer, and she refused to give that DNA to Wilkins, okay, in the same lab. This is pretty bad behavior. On the pretense that she'd work [INAUDIBLE] and so she was entitled to keep the DNA. Which was a little bit absurd because Signer sent it to the London lab. I mean, he didn't care who. So they were all three in a rush. So they knew the London group would send the paper. So they send their paper assuming that everything would fit, more or less. But the model was not built on the images of London. Nobody model builds on any other than putting bits and pieces of cardboard together until they fit. Model building.