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
Photo 51 her own data, had Watson and Crick not obtained Gosling's image, is a hotly debated topic, made more controversial by the negative caricature of Franklin presented in the early chapters of Watson's history of the research on DNA structure, "The Double Helix". Watson admitted his distortion of Franklin in his book, noting in the epilogue: "Since my initial impressions about [Franklin], both scientific and personal (as recorded in the early pages of this book) were often wrong, I want to say something here about her achievements." Photo 51 Photograph 51 is the nickname given to an X-ray diffraction image of