Discovery of the DNA Double Helix
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Questions and Answers

Who showed Watson the famous image known as Franklin's Photo 51?

  • Pauling
  • Watson and Crick
  • Wilkins (correct)
  • Chargaff
  • What did Franklin's X-ray crystallography data show about the symmetry of DNA?

  • It had rotational symmetry (correct)
  • It had linear symmetry
  • It had mirror symmetry
  • It had no symmetry
  • What did Chargaff's analysis of DNA chemical composition reveal?

  • Adenine always pairs with cytosine
  • Guanine is the most abundant base in DNA
  • Adenine and thymine amounts are always equal (correct)
  • Adenine and thymine never occur together
  • What challenge did Watson face when building models based on Crick's insight about the symmetry of DNA?

    <p>The bases couldn't pair in the way Watson had proposed</p> Signup and view all the answers

    What did the discovery of the double helix structure explain?

    <p>The stability of life and its mutability in evolution</p> Signup and view all the answers

    Who were the scientists that joined forces to discover the structure of the gene?

    <p>James Watson and Francis Crick</p> Signup and view all the answers

    Why was DNA often dismissed as the biological molecule involved in inheritance?

    <p>Due to its apparent simplicity</p> Signup and view all the answers

    What hindered the partnership between Maurice Wilkins and Rosalind Franklin?

    <p>Conflicting goals</p> Signup and view all the answers

    Why did the Cavendish Lab director not want his equipment used for DNA analysis?

    <p>Conflict with researchers at King's College</p> Signup and view all the answers

    Which scientist was also working on DNA structure in California, causing concern for Watson and Crick?

    <p>Linus Pauling</p> Signup and view all the answers

    What did Watson and Crick initially build a model of in 1951?

    <p>The symmetry of DNA</p> Signup and view all the answers

    Who showed Watson the famous image known as Franklin's Photo 51?

    <p>Maurice Wilkins</p> Signup and view all the answers

    What challenge did Watson face when building models based on Crick's insight about the symmetry of DNA?

    <p>The bases couldn't pair in the way Watson had proposed</p> Signup and view all the answers

    According to Chargaff's analysis of DNA chemical composition, what was always equal?

    <p>Guanine (G) and Cytosine (C)</p> Signup and view all the answers

    What did the discovery of the double helix structure explain?

    <p>The stability of life and its mutability in evolution</p> Signup and view all the answers

    What technique was used to solve molecular structures, but the Cavendish Lab director did not want his equipment used for DNA analysis?

    <p>X-ray crystallography</p> Signup and view all the answers

    What was the apparent reason for DNA being often dismissed as the biological molecule involved in inheritance?

    <p>Apparent simplicity</p> Signup and view all the answers

    What did Maurice Wilkins and Rosalind Franklin conflict over when working on DNA structure at King's College?

    <p>Publication priority</p> Signup and view all the answers

    Who was also working on DNA structure and caused concern for Watson and Crick, as they were worried he would solve the structure before them?

    <p>Linus Pauling</p> Signup and view all the answers

    What molecular structure was believed to be made of either DNA or protein in the early 20th century?

    <p>Nucleic acid</p> Signup and view all the answers

    Study Notes

    • In the early 20th century, scientists were trying to unlock the secrets of inheritance and the biological molecule involved was yet to be discovered.
    • James Watson, a 23-year-old American scientist, and Francis Crick, an Englishman trained as a physicist, joined forces in 1951 at the Cavendish Laboratory in Cambridge, England, to discover the structure of the gene.
    • Watson was known for his love of science, determination, and unconventional behavior, while Crick was a quiet, thoughtful scientist with a strong interest in biology.
    • The gene's structure was believed to be made of either DNA or protein, but DNA was often dismissed due to its apparent simplicity.
    • X-ray crystallography was a powerful technique used to solve molecular structures, but the Cavendish Lab director did not want his equipment used for DNA analysis, as a group at King's College was already doing so.
    • Maurice Wilkins and Rosalind Franklin were working on DNA structure at King's College. Wilkins wanted to lead the project, but Franklin believed it should be hers. Their conflicting goals hindered their partnership.
    • Linus Pauling, a renowned physical chemist, was also working on DNA structure in California. Watson and Crick were concerned that he would solve the structure before them.
    • In 1951, Watson and Crick built a model of DNA as a helix, but it was dismissed by Franklin due to inaccurate measurements provided by Watson.
    • In January 1953, news came that Pauling was preparing a paper on DNA structure, and Watson rushed to London to find that Franklin was uninterested in his findings.
    • Watson then encountered Wilkins, who showed him a famous image, Franklin's Photo 51, which revealed the helical structure of DNA. Watson immediately recognized its significance.- In the late 1940s and early 1950s, Watson and Crick were working on understanding the structure of DNA.
    • Franklin's X-ray crystallography data showed the symmetry of DNA, leading Crick to the insight that the sugar phosphate backbones had to run in opposite directions.
    • Watson started building models based on this new understanding, but faced a challenge when a colleague pointed out that the bases couldn't pair in the way Watson had proposed.
    • Chargaff's analysis of DNA chemical composition revealed that the amounts of adenine (A) and thymine (T) in DNA were always equal, as were the amounts of guanine (G) and cytosine (C).
    • Watson went to the lab on a Saturday morning and experimented with cardboard cutouts to create a model with complementary base pairing, which explained how genetic information is stored and how mutations occur.
    • The structure of the double helix, revealed in 1953, explained both the stability of life and its mutability in evolution.
    • The discovery of the double helix structure was celebrated around the world and led to a Nobel Prize nine years later.
    • The discovery opened up a new world for biologists and paved the way for decoding the mysteries of life.

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    Test your knowledge about the discovery of the DNA double helix structure and the scientists involved, including James Watson, Francis Crick, Rosalind Franklin, and Maurice Wilkins. Learn about the events that led to one of the most significant breakthroughs in biology.

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