How was it determined that the structure of DNA is a double helix with the two strands held together by hydrogen bonds formed between complementary nitrogenous bases?

Video transcript

Hi everyone. Let's take a look at this practice problem together. Rosalind Franklin gave the first idea of regarding the three dimensional structure of D. N. A. Using a method known as So recall that Franklin was an expert in a method called x ray diffraction. And she and Maurice Wilkins used this to discover the D. N. A. Structure and although she didn't receive a nobel prize for it, it was Watson and Crick who used her findings to come up the model of D. N. A. They did this without her permission though, so knowing franklin and her history is important. So let's review our method options. We've got a gel electrophoresis. Now recall that this is a process that uses a jail plate with electric current to separate D. N. A fragments by their charge and their size. So this is not going to give any useful information about the structure of D. N. A. Then we've got C particle bombardment. Now this is a method used to transfer genes into a cell and it's done by shooting millions of metal particles coated with DNA. Using a gene gun. This would also not tell us any information about the structure of D. N. A. So C. Is not correct. Then we've got option B. X ray crystallography. Now this is the X ray diffraction. This is a process of using x rays to bombard crystallized DNA molecules and you view the resulting diffraction pattern on a film. So this is our answer. This is what franklin used. Alright, everyone, I hope you found this helpful. And I'll see you soon for the next practice problem.