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
Non-helical models of DNA structure as evidence that the strands were plectonemically wound together ("i.e.," topologically linked). The publication of the Rodley structure produced a small but significant ripple of interest in the molecular biological community. However, the level of interest was sufficiently high so that Crick - by that time one of the world’s most influential scientists - publicly suggested that the SBS structure (whose existence he doubted) should be laid to rest by intentionally creating it. Then, he reasoned, its properties could be ascertained, and then shown to be abnormal with respect to the known properties of native DNA. An investigation by Stettler