Watson and Crick demonstrated the three-dimensional double helix molecular structure of the DNA (deoxyribonucleic acid) with reference to Erwin Chargaff and Rosalind Franklin. Watson and Crick used the results obtained from Chargaff and Franklin experiments to explain DNA structure.
Watson and Crick said that the DNA structure has two antiparallel strands. Each strand has made up of four different nucleotides and these nucleotides are twisted into the shape of a double helix. However, Watson and Crick could not explain without the conventional experimentation of “Erwin Chargaff and Rosalind Franklin.”
“Erwin Chargaff” experimentally demonstrated that guanine pairs with cytosine with three hydrogen bonds (G≡C) and adenine pairs with thymine with two hydrogen bonds (A=T). According to this experiment, he proved that the amount of cytosine is equal to guanine, and the amount of adenine is equal to thymine. The rule is called Chargaff’s or Base pairing rule.
The biophysicist Rosalind Franklin used “x-ray diffraction technique” to deduce the structure of DNA. According to this technique, Franklin explained that the structural integrity of DNA is maintained by phosphodiester bonds. These bonds are formed between the deoxy ribose sugar and phosphate groups. From her data, Watson and Crick concluded that DNA exists in a twisted conformation and they also explained the dimensions of DNA too.
Apart from the above experiments, Meselson and Stahl explained a major mechanism that explains DNA replication. They conducted an experiment called N14 and N15 experiment. Based on the results that were obtained from their experiment, Meselson and Stahl stated that DNA replication occurs in a semiconservative mode of replication.