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
Molecular models of DNA 1953. That same year, Maurice F. Wilkins, A. Stokes and H.R. Wilson, reported the first X-ray patterns of "in vivo" B-DNA in partially oriented salmon sperm heads. The development of the first correct double helix molecular model of DNA by Crick and Watson may not have been possible without the biochemical evidence for the nucleotide base-pairing ([A---T]; [C---G]), or Chargaff's rules. Although such initial studies of DNA structures with the help of molecular models were essentially static, their consequences for explaining the "in vivo" functions of DNA were significant in the areas of protein biosynthesis and the quasi-universality of the