Discovering the double helix structure of DNA, James Watson, video with 3D animation and narration
James Watson used cardboard cutouts representing the shapes of the DNA bases to figure out how bases pair. He realized that the adenine-thymine and cytosine-guanine pairings fit all the dimensions. (DNAi Location: Code > Finding the structure > Pieces of the puzzle > Watson's base pairing)
The Cavendish shop was to build us some tin models and that took too long, and, you know, finally in desperation, I made some out of cardboard. I began moving them around and I wanted an arrangement, you know, where I had a big and a small molecule. So, how did you do it? Somehow you had to form link bonds. So, here is A and here's T, and I wanted this hydrogen to point directly at this nitrogen so I had something like this. So then I went to the other pair. I wanted this nitrogen point to this one and it went like this. They looked the same. And you could put one right on top of the other. We knew if we just, even if we go up to the ceiling, we're building a tiny fraction of a molecule. Hundreds of millions of these base pairs in one molecule, all fitting into this wonderful symmetry, which we saw the morning of February 28, 1953.
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- ID: 15492
- Source: DNALC.DNAi
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James Watson talks about how he worked out the base pairing of DNA.
James Watson and Francis Crick explain how they solved the structure of DNA. Erwin Chargaff explain how he measured the levels of each of the four nitrogenous bases.
Deoxyribose and phosphate molecules form the uprights and nucleotide pair form the rungs of the DNA ladder.
In 1953, James Watson and Francis Crick solved the structure of DNA. This beautiful molecule sparked a new era of research into the code of life.
DNA base pairs
Because it contains the directions for assembling the components of the cell, DNA is often thought of as the "instruction book" for assembling life.
1953 picture of Francis Crick (L) and James Watson (R) walking along the backs of King's College in Cambridge.
James Watson and Francis Crick, Cambridge University, 1953
Erwin Chargaff found that in DNA, the ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal. This parity is obvious in the final DNA structure.
The DNA molecule is shaped like a twisted ladder.