24 Describe the data available to Watson and Crick that help

24: Describe the data available to Watson and Crick that helped them in their model.

NOTE: Please site the sources

Solution

Watson and Crick discovered the helical structure of DNA in 1953. Watson and Crick at an early stage in careers gained knowledge in various fields of science like genetics, biochemistry, chemistry, physical chemistry, and X-ray crystallography. They draw the experimental results of others, took scietific backgrounds in physics , X ray crystallography and genetics. The information available to them is -

Many of their attempts failed till Jerry Donohue, a visiting physical chemist from the United States pointed out that the configuration of rings of carbon, nitrogen, hydrogen, and oxygen in thymine and guanine was incorrect. With Donohue\'s advice on February 28, 1953, Watson arranged two bases into their correct form by moving hydrogen atom from position where it bonded to oxygen to a neighboring position where it is bonded with nitrogen. After placing he realised that the A T and GC pairs fitted between the two helical sugar-phosphate backbones of DNA, the outside rails of the ladder. The bases connected at right angles and were structurally similar as shown in X-ray evidence.

Source-

The Francis Crick Papers, The Discovery of the Double Helix, 1951-1953