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DNA Pioneer Francis Crick Passes Away
Neil Halelamien writes "Francis Crick, who discovered the structure of DNA with James Watson, Rosalind Franklin, and Maurice Wilkins, passed away Wednesday in San Diego. His co-discovery of 'the secret of life' made him one of the most influential scientists of all time. In more recent years, he shifted his research efforts from molecular biology to neuroscience, with a particular interest in the question of the neural basis of consciousness."
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Did he use his own, or watson's, DNA under the microscope to make the discovery?
Moo.
...that is, life arriving at earth via DNA sent out from aliens.
More on that theory in Wikipedia. Interesting stuff!
The Army reading list
You sir, are both insensitive, and a clod.
It would be sincerely appreciated if you would leave the rest of us to our grief.
Thank you.
Take a look at this link for some of what the parent is talking about:
n a.html
http://www.ba-education.demon.co.uk/for/science/d
http://nyamenation.org/
Crick didn't even know what Watson was doing the night that he made the mock-up. As an interesting note there was a bit of slack in the way the wooden "lego" was made that allowed the correct answer to emerge despite a slight flaw in the idea.
Lastly I think your joke was refering to Craig Venter that used his own DNA at Celera, Right?. I have a lot of respect for Venter despite his slight Megalomaniac tendencies.
Help fight continental drift.
In terms of making the discovery, Rosalind Franklin took pictures of the structure of DNA, Watson and Crick just looked at the pictures and deduced the structure. So I guess you could patent the picture taking process. Toodles.
In nature, there are neither rewards or punishments, there are only consequences.
It seems to me, and this is totally a gut feeling, that the basic 'units of consciousness' will be in nueral superstructers. I'm actually a supporter of a top down approach -- trying to tear apart things that are apparent to us in our consciousness --Woah! How about getting a definition of consciousness first -- and then trying to find what neurons are responsible for them. We're had more success this way -- finding which parts of the brain light up when we use language, recognize faces, solve math problems, etc.
Furthermore, all the models of nuerons thinking use them as logic gates. That seems to imply to me that some consciousness researchers think the brain is a huge Turing machine -- again, this doesn't seem right to me, because Goedel's Theorem, as I understand, shows there are things a Turing machine can't compute. And if humans can understand Goedel's theorem, we must have something qualitatively different than a Turing machine up there.
Computers are useless. They can only give you answers.
-- Pablo Picasso
Attached is the famous Watson and Crick paper.
Also note - Obituary Here: http://www.nature.com/news/2004/040726/full/040726 -12.html
Molecular structure of Nucleic Acids
WATSON, J. D. & CRICK, F. H. C.
Medical Research Council Unit for the Study of Molecular Structure of Biological Systems, Cavendish Laboratory, Cambridge.
A Structure for Deoxyribose Nucleic Acid
We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest.
A structure for nucleic acid has already been proposed by Pauling and Corey1. They kindly made their manuscript available to us in advance of publication. Their model consists of three intertwined chains, with the phosphates near the fibre axis, and the bases on the outside. In our opinion, this structure is unsatisfactory for two reasons:
(1) We believe that the material which gives the X-ray diagrams is the salt, not the free acid. Without the acidic hydrogen atoms it is not clear what forces would hold the structure together, especially as the negatively charged phosphates near the axis will repel each other.
(2) Some of the van der Waals distances appear to be too small.
Another three-chain structure has also been suggested by Fraser (in the press). In his model the phosphates are on the outside and the bases on the inside, linked together by hydrogen bonds. This structure as described is rather ill-defined, and for this reason we shall not comment on it.
We wish to put forward a radically different structure for the salt of deoxyribose nucleic acid. This structure has two helical chains each coiled round the same axis (see diagram). We have made the usual chemical assumptions, namely, that each chain consists of phosphate diester groups joining ß-D-deoxyribofuranose residues with 3',5' linkages. The two chains (but not their bases) are related by a dyad perpendicular to the fibre axis. Both chains follow right- handed helices, but owing to the dyad the sequences of the atoms in the two chains run in opposite directions. Each chain loosely resembles Furberg's2 model No. 1; that is, the bases are on the inside of the helix and the phosphates on the outside. The configuration of the sugar and the atoms near it is close to Furberg's 'standard configuration', the sugar being roughly perpendicular to the attached base. There is a residue on each every 3.4 A. in the z-direction. We have assumed an angle of 36 between adjacent residues in the same chain, so that the structure repeats after 10 residues on each chain, that is, after 34 A. The distance of a phosphorus atom from the fibre axis is 10 A. As the phosphates are on the outside, cations have easy access to them.
Figure 1
This figure is purely diagrammatic. The two ribbons symbolize the two phophate-sugar chains, and the horizonal rods the pairs of bases holding the chains together. The vertical line marks the fibre axis.
The structure is an open one, and its water content is rather high. At lower water contents we would expect the bases to tilt so that the structure could become more compact.
The novel feature of the structure is the manner in which the two chains are held together by the purine and pyrimidine bases. The planes of the bases are perpendicular to the fibre axis. They are joined together in pairs, a single base from one chain being hydrogen-bonded to a single base from the other chain, so that the two lie side by side with identical z-co-ordinates. One of the pair must be a purine and the other a pyrimidine for bonding to occur. The hydrogen bonds are made as follows : purine position 1 to pyrimidine position 1 ; purine position 6 to pyrimidine position 6.
If it is assumed that the bases only occur in the structure in the most plausible tautomeric forms (that is, with the keto rather than the enol configurations) it is found that only specific pairs of bases can bond together. These pairs a
I find it incredible that such a brilliant scientist would delve into the realm of "what makes conciousness". On the other hand, after you discover something as significant as DNA, I guess you're obligated to work on something at least as important for your next assignment.
What makes it incredible for me to believe he would try to explain conciousness is the fact that there are philisophical issues. What if Christians are right and man has an imperishable soul? If it exists it would be the seat of conciousness. Otherwise you wouldn't be you after you're dead. This means that the brain is nothing but a "soul interface" which contains nothing of eternal value. This would make for some very frustrating research!!!
"Meaningless!, Meaningless!" says the Teacher. "Utterly meaningless!"
I think that the famous double helix result should not be taught as fact and so readily accepted by everyone. I'm not saying it's untrue, I'm just saying we ought to maintain a healthy scientific skepticism toward things that don't have an irrefutably strong case based on empirical evidence backing them, and this one doesn't.
When you try reverse an x-ray diffraction pattern back into the 3D structure of the thing that caused it, at some point you have to solve a Bessel function. There are many solutions to that Bessel function, each of which could have produced that pattern. The best solution is the one that dictates a 3D structure that fits other observations outside of the diffraction pattern. For this particular experiment (if you read the paper they published), the first solution to the Bessel function they used implies two strands wound around each other. The second solution implies four, the third implies six strands, etc.
Watson and Crick, in that paper, assumed the first solution was the best one, even though the second one is possible too. (The third and higher solutions are not possible because in the 3D space-filling model there's physically no room for 6 or more strands within that volume of space.) As it happens, the second solution, which suggests a four-stranded helical model, seems to fit the rest of the data in that paper and its references better than the two-stranded one.
There's other evidence out there to suggest the double-stranded model is not necessarily correct, too...above I'm only talking about what's in the original paper itself. I'm not saying the conclusion is wrong, I'm only saying that I think that biologists have accepted this model as fact too readily, based on mathematics that most biologists can't follow (how many bio Ph.D.s can solve Bessel functions?). I'm suggesting there's not enough empirical evidence to characterize this double-stranded helical model as fact, though. We all ought to be more skeptical...there is no good explanation I know of for why they picked the first solution over the second, and until it's addressed the question should remain open. That's just good science.
I wonder how much this matters anyway, though. Ok, so DNA coils up into a helix in a crystal under certain experimental conditions. Does that mean it maintains the same structure in other situations, such as in vivo? Anyone who's studied molecular bio knows that molecular biological structures adopt lots of different forms that are highly dependent on the environment in which they find themselves.
Still, this is more a comment on the scientific community's shortcomings than Watson or Crick specifically. Does anyone out there know of any significant discoveries based on Watson and Crick's famous advance? What technologies/medicines/whatever has been developed as a result? This seems like a good way to honor their contribution.
sev
but have you considered the following argument: shut up.
We had some fabulous conversations about the nature of consciousness last summer in La Jolla, and he went on for hours and hours about the work his friend Christoff Koch was doing at Caltech - but the conversation was never about taking credit for ideas or who did what.
Wilkins went behind Rosalind Franklin's back and gave copies of her image data to James Watson. I don't believe that Crick even knew that he was looking at data without her permission. Regardless, he isn't the type of person to deny the credit she was due, nor to be shy about the fact that it was mostly he who deciphered the X-ray diffraction images. He was beyond uninterested in the politics side of science.
Like Dr. Crick, I studied physics and once thought I wanted to be a physicist. We discussed this, and I explained my reasons for not pursuing graduate studies these days, due to the excessive politics involved and the nature of funding, being beholden to a professor's interests and so on. And he agreed that if he were graduating from college today, he might feel the same way.
As for the "right bastard" part, like many scientists, and lots of people on Slashdot too, Dr. Crick was no social genius. He liked socializing with academics and people who would talk about ideas with him. But he always seemed to be a very decent person to me.
Goodbye to a truly great man. I met Dr. Crick twice. He was the only scientist I ever met who awed me so completely that I could never call him by his given name. Dr. Crick was involved in essentially every major breakthrough in molecular genetics between about 1955 and the end of the '60s. The structure of DNA, the "Central Dogma," triplet coding, as a very few high points among the accomplishments where his work was central. If you read "The Eighth Day of Creation," the breathtaking history of molecular genetics, you find that for those years it is largely a history of the work of Francis Crick. Following that, he nearly invented the new field of the analysis of the biological correlates fo consciousness. Truly a giant of intellectual achievement, I consider him one of the 5 greatest scientists to have ever lived. He was also a truly generous spirit. Both times I talked with him, he took a genuine interest in my work, discussed in detail my problem, and my experiments, and made serious and thoughtful comments on what I was doing. He didnt have to; I was a graduate student grinding away at what at that time looked like an obscure backwater project. He will be missed. I for one will be hoisting a couple in his honor over the next few days.