Ans.Watson-Crick Model of DNA
In 1953, James Watson and Francis Crick proposed the structure of DNA. According to the Watson Crick nodel a DNA molecule consists of two Proteins polynucleotide strands. These (Histories) strands are coiled around each other in the form of a double
helix.There is a phosphate-sugar backbone on the outside of double helix, and
the nitrogenous bases are on the inside.