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
Rosalind Franklin and DNA and B forms of DNA were composed of two helical chains. By then, James Watson and Francis Crick at the Cambridge University had built a correct double helical model of DNA, based on her experimental data. The discovery of the structure of DNA in 1953 is regarded as "the greatest and most important scientific discovery of the 20th Century". Francis Crick, James Watson and Maurice Wilkins received the Nobel Prize in Physiology or Medicine in 1962 for the discovery. This discovery laid the foundation for modern biology, including medical and molecular researches. The discoverers earned a lasting worldwide fame. But