DNA History & Structure

Cytosine (C)

Guanine (G)

Thymine (T)

Uracil (U)

10%

20%

30%

40%

20%

30%

40%

60%

Rosalind Franklin

Erwin Chargaff

James Watson

Francis Crick

Watson and Crick discovered DNA's structure using only their own ideas.

Franklin's X-ray crystallography techniques were not important to the discovery.

Chargaff's rules for base pairing were ignored in the discovery.

Watson and Crick built on the work of other scientists to discover DNA's double helix shape.

Phosphate

Sugar

Nitrogenous base

Fatty acid

Adenine-Thymine

Cytosine-Guanine

Thymine-Guanine

Adenine-Cytosine

5' end is the head, 3' end is the tail, determined by specific carbon atoms in the sugar molecule

3' end is the head, 5' end is the tail, determined by nitrogenous bases

5' end is the head, 3' end is the tail, determined by phosphate groups

3' end is the head, 5' end is the tail, determined by hydrogen bonds