-A nucleotide consists of a five carbon sugar (ribose) with a phosphate group attached to carbon number 5, and a nitrogen base attached to carbon number 1 using a glycosyl bond.
-There are 4 base pairs (2 purines: 2 rings, and 2 pyramidines: 1 ring).
-They are grouped together as complimentary base pairs:
Cytosine (pyramidine) with Guanine (purine)
Thymine (pyramidine) with Adenine (purine)
-DNA consists of two anti-parallel strands in a double helical structure connected by hydrogen bonds.
-found Adenine and Thymine, Cytosine and Guanine, Purines and Pyramidines existed in equal proportions
1953—Rosalin Franklin, Maurice Wilkins
-used x-ray diffraction to analyse DNA structure
-suggested double helical structure (2nm diameter, 3.4nm helical twist)
-Wilkinson presented data to Watson and Crick before it was published
-presented DNA structure based on Chargaff, Franklin and Wilkin’s observations