... bases) were known * The sugar (S) and phosphate (P) were known to be connected together to form a backbone. The bases (B) were known to be stuck out to the side, attached to the sugar of the backbone by one of their N atoms: * Rosalind Franklin had pointed out that phosphate has negative charges at cellular PHs. Since these charges would repel each other she insisted that the sugar-phosphate backbone was on the outside of the molecule * Hydrogen bonds had been shown to be very important in determining the shapes of proteins and it was expected that they would be important in DNA as well * Rosalind Franklin had taken excellent x-ray diffraction pictures of DNA. The pictures had a distinctive pattern that was known from theory (developed by Francis Crick) to be due to a helical structure (2 or more strands spiralling around each other) * Erwin ...

See this essay or coursework document in full right now