James Watson & Francis Crick 17.2 – The Structure of Nucleic Acids   DNA – The Double Helix see fig 17.12 and 17.13, pp. 574-575

Maurice Wilkins (1916- ) Like Crick, New Zealand-born Wilkins trained as a physicist, and was involved with the Manhattan project to build the nuclear bomb. Wilkins worked on X-ray crystallography of DNA with Franklin at King's College London, although their relationship was strained. He helped to verify Watson and Crick's model, and shared the 1962 Nobel with them.

What makes up the double helix?

Subunits of the helix: Nucleotides

2 types of Nucleotides; Purines & Pyrimidines

3 parts of a nucleotide

Varying parts in a nucleotide 2 types of sugar All Phospate groups same 5 different nitrogenous bases

How nucleotide form helix

How nucleotide form helix

How nucleotide form helix

T-A 2 hydrogen bonds C-G 3 hydrogen bonds

Erwin Chargaff (1905-2002) Chargaff discovered the pairing rules of DNA letters, noticing that A matches to T and C to G. He later criticized molecular biology, the discipline he helped invent, as "the practice of biochemistry without a licence", and once described Francis Crick as looking like "a faded racing tout".

Replication of DNA. Semi-conservative