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 was a general consensus at the time that they were at the inside); and the other is that DNA exists in two forms, a crystalline (dry form) A-DNA and a hydrated (wet form) B-DNA. With her PhD student Raymond Gosling, she produced a series of X-ray images of DNA. The photograph (number 51, hence, popularised as Photo 51) of B-DNA taken in May 1952 was especially crucial. X-ray crystallography did not immediately show the precise helical structure. Franklin chose to work on A-DNA, while B-DNA was given to Maurice Wilkins. By the early 1953, Franklin was aware that both A