Life their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts. In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed. DNA was first isolated by Friedrich Miescher in 1869. Its molecular structure was identified by James Watson and Francis Crick in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Rosalind Franklin. Life is
Maurice Wilkins Raymond [Gosling] and I got a clear crystalline X-ray pattern I was very eager to continue that work ... Trying to understand 'what really happened' when a very admirable scientist [Randall] models himself on Napoleon is not easy ... [but the letter] was very damaging to her and to me". By November 1951, Wilkins had evidence that DNA in cells as well as purified DNA had a helical structure. Alex Stokes had solved the basic mathematics of helical diffraction theory and thought that Wilkins's X-ray diffraction data indicated a helical structure in DNA. Wilkins met with Watson and Crick and