What is the text structure of the three paragraphs above…
They were hardly modest, these two brash young scientists who in 1953 declared . . . that they had “found the secret of life.” But James Watson and Francis Crick’s claim was a valid one, for they had in fact discovered the structure of DNA, the chemical that encodes instructions for building and replicating almost all living things.
Watson and Crick’s discovery didn’t come out of the blue. As early as 1943 Oswald Avery proved what had been suspected: that DNA . . . carries genetic information. But no one knew how it worked.
[Then, in 1951 at] King’s College in London, Rosalind Franklin and Maurice Wilkins were studying DNA. Wilkins and Franklin used X-ray diffraction as their main tool—beaming X-rays
through the molecule yielded a shadow picture of the molecule’s structure