DNA archaea) store their DNA only in the cytoplasm. Within eukaryotic 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 first identified by James Watson and Francis Crick at the Cavendish Laboratory within the University of Cambridge in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin. DNA is used by researchers as a
Francis Crick to peptide bonds in proteins and the structure of nucleotides in DNA. In 1951 and 1952, together with William Cochran and Vladimir Vand, Crick assisted in the development of a mathematical theory of X-ray diffraction by a helical molecule. This theoretical result matched well with X-ray data for proteins that contain sequences of amino acids in the alpha helix conformation. Helical diffraction theory turned out to also be useful for understanding the structure of DNA. Late in 1951, Crick started working with James Watson at Cavendish Laboratory at the University of Cambridge, England. Using "Photo 51" (the X-ray diffraction results