What background information did Watson and Crick have made available for developing a model of DNA? What was their contribution?

Watson and Crick have made information available for developing a model of DNA which are as follow:

1. Chargaff’s rule: They used Chargaff’s rule of base pairing which showed Adenosine forms bond with Thymine (A&T) and Guanine bonds with Cytosine (G & C).

2. Wilkins and Franklin’s rule: This rule was used to know that DNA has a diameter of 20 Å, a regular helix structure with 34Å distance and 10 base pairs of nucleotides in each turn of the spiral.

3. X-ray crystallography is was used to study DNA’S physical structure.

Contribution:

1. They discovered DNA was a double helix structure.

2. They also discovered the complementary base pairing by hydrogen bonds.