A restriction fragment is a DNA fragment resulting from the cutting of a DNA strand by a restriction enzyme (restriction endonucleases), a process called restriction.
 Each restriction enzyme is highly specific, recognising a particular short DNA sequence, or restriction site, and cutting both DNA strands at specific points within this site.
 Most restriction sites are palindromic, (the sequence of nucleotides is the same on both strands when read in the 5' to 3' direction), and are four to eight nucleotides long.
 Many cuts are made by one restriction enzyme because of the chance repetition of these sequences in a long DNA molecule, yielding a set of restriction fragments.
 A particular DNA molecule will always yield the same set of restriction fragments when exposed to the same restriction enzyme.
 Restriction fragments can be analyzed using techniques such as gel electrophoresis or used in recombinant DNA technology.
National DNA Day is a holiday celebrated on April 25.
 It commemorates the day in 1953 when James Watson, Francis Crick, Maurice Wilkins, Rosalind Franklin and colleagues published papers in the journal Nature on the structure of DNA.
 Furthermore, on that day in 2003 it was declared that the Human Genome Project was very close to complete, and "the remaining tiny gaps [we]re considered too costly to fill."
Photograph 51 is an award-winning play by Anna Ziegler.
 "Photograph 51" opened in the West End of London in September 2015.
 The play focuses on the often-overlooked role of x-ray crystallographer Rosalind Franklin in the discovery of the double helix structure of DNA while working at King's College London.
 This play won the 3rd "STAGE" International Script Competition in 2008.
 The title comes from "Photo 51", the nickname given to an X-ray diffraction image taken by Raymond Gosling in May, 1952, under the supervision of Rosalind Franklin.
 The one-act play runs for 95-minutes with no intermission.
What Mad Pursuit: A Personal View of Scientific Discovery is a book published in 1988 and written by Francis Crick, the English co-discoverer in 1953 of the structure of DNA.
 In this book, Crick gives important insights into his work on the DNA structure, along with the Central Dogma of molecular biology and the genetic code, and his later work on neuroscience.
Sven Verner Furberg (16 April 1920 – 15 March 1983) was a Norwegian chemist, biologist and crystallographer who first proposed the helical structure of DNA.
 Furberg suggested this structure in 1949, which he referred to as a "zig-zag" chain.
 In 1952, his structure of DNA was published in the journal Acta Chemica Scandinavica.
 In this paper, he deduced that DNA forms a double helix from the crystal structure and density value of nucleosides and other related molecules.
 A year later, this paper was cited by James Watson and Francis Crick in "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid".
Anne Colquhoun Sayre (April 10, 1923 – March 13, 1998) was an American writer well known for her biography of Rosalind Franklin, one of the discoverers of the structure of DNA.
 She was married to an American crystallographer David Sayre (1924–2012).
 Her literary contributions are in short stories, the earnings from which she supported her husband during his PhD course.
 She achieved her lifelong educational ambition of getting a law degree in her early 50s.
 She ultimately became justice of the local court in Riverhead.
 She was a lifelong friend of Franklin, who played a key role in the discovery of the chemical structure of DNA.
 A strong feminist, her 1975 book "Rosalind Franklin and DNA" became an exposition of the account of sexism in the scientific community on one hand, and the true genius of the British Chemist Rosalind Franklin in her contributions to molecular biology on the other hand.
Alexander (Alec) Rawson Stokes (27 June 1919 – 5 February 2003) was a co-author of the second of the three papers published sequentially in "Nature" on 25 April 1953 announcing the presumed molecular structure of DNA.
 The first was authored by Francis Crick and James Watson, and the third by Rosalind Franklin and Raymond Gosling.
 The Nobel Prize in Physiology or Medicine was awarded in 1962 to Crick, Watson, and Wilkins for this work.
James Dewey Watson (born April 6, 1928) is an American molecular biologist, geneticist and zoologist, best known as one of the co-discoverers of the structure of DNA in 1953 with Francis Crick and Rosalind Franklin.
 Watson, Crick, and Maurice Wilkins were awarded the 1962 Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material".
Rosalind Elsie Franklin (25 July 192016 April 1958) was an English chemist and X-ray crystallographer who made contributions to the understanding of the molecular structures of DNA (deoxyribonucleic acid), RNA (ribonucleic acid), viruses, coal, and graphite.
 Although her works on coal and viruses were appreciated in her lifetime, her contributions to the discovery of the structure of DNA were largely recognised posthumously.
Francis Harry Compton Crick (8 June 1916 – 28 July 2004) was a British molecular biologist, biophysicist, and neuroscientist, most noted for being a co-discoverer of the structure of the DNA molecule in 1953 with James Watson, work which was based partly on fundamental studies done by Rosalind Franklin, Raymond Gosling and Maurice Wilkins.
 Together with Watson and Maurice Wilkins, he was jointly awarded the 1962 Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material".

Question: Who was Francis Crick's co-discoverer of the structure of the DNA molecule which was based partly on fundamental studies done by English chemis and X-ray crystallographer Rosalind Franklin?
Answer: James Watson