Tuesday, January 3, 2012

What was Rosalind Franklin's contribution to Watson & Crick's Theory?

Use citations.
Be ready for a 4 question quiz by Wednesday.


  1. Rosalind Franklin was a scientist that worked closely with Maurice Wilkins. Together the two study DNA structures using x-ray crystallography to capture photographs of DNA strands. Observing these photographs carefully, they concluded that they were looking at form B of DNA. Two strands of DNA where present, and the phosphate groups were turned away from each other. With this new discovery, the scientific world was certainly doing well. In just a short time after, Franklins work influenced two scientists; Waston and Crick. Franklins work was very significant to the discovery of the double helix, by Watson and Crick. Knowing this, Franklin took the double helix model and compared it to her photographs. The facts were there, a double helix did exist in DNA. It is because of them that today we understand so much about life.


    "The instant I saw the picture my mouth fell open and my pulse began to race.... the black cross of reflections which dominated the picture could arise only from a helical structure... mere inspection of the X-ray picture gave several of the vital helical parameters." - Rosalind Franklin



    Biology : Exploring Life text book Chapter 11.2

  2. Watson & Crick used X-ray diffraction pictures obtained by by Rosalind Franklin to help form their theory.

    "The Double Helix Structure of DNA." Wiley Online Library. Web. 03 Jan. 2012. .

  3. What was Rosalind Franklin's contribution to Watson & Crick's Theory?
    -It all started when watson and crick made a model to try to explain DNA's structure with tin and wire, But Rosalind Franklin's contribution to Watson & Cricks theory began when wastson saw franklins x-ray crystallography photos of DNA . from this watson and franklin started working together to create a new model in which two strands of nucleotides wind together to form a double helix. (the first model made by watson and crick failed, because they failed to explain DNA's chemical properties.) anyways franklin also helped forming a hypothesis which states, and i quote " That the nitrogenous base that aligned across two strands formed hydrogen bonds". their new model was a success, it described DNA's chemical properties and successfully represented DNA's structures.

    * Citations: Exploring life biology text book. chapter 11 section 2




  4. Vanessa Estrada, second period.January 3, 2012 at 3:03 PM

    Rosalind Franklin's contribution to Watson and Crick's theory was provided through x-ray crystallography used as a model. Franklin's contribution was the root of Watson and Crick's success.

    History of Molecular Biology
    Michel Morange
    published: 15 DEC 2009

  5. Watson and Crick's theory was the shape of the DNA molecule, which was sort of like a twisted ladder with the nitrogenous bases as the rungs. Rosalind Franklin was one person who contributed to this theory. She discovered that DNA could be crystallized into two forms - A and B. After examining both forms using a technique called x-ray crystallography, she discovered three things about DNA's structure. According to http://www.accessexcellence.org/RC/AB/BC/Rosalind_Franklin.php, she discovered:

    "1. That the sugar-phosphate backbone of DNA lies on the outside of the molecule, not the inside as was previously thought.

    2. That the helical structure of DNA has two strands, not three as proposed in competing theories.

    3. Quantitative details about the shape and size of the double helix."


  6. Kathlyn Larralde P2January 3, 2012 at 4:27 PM

    Rosalind Franklin's contribution to Watson & Crick's theory, with the construction of the double helix DNA model, where she found that DNA was two strands instead of 3 on how other scientist believed. In which she called strand A and B because they had different patterns. Using both the crystallographic theory and chemical reasoning she discovered important basic facts about its structure. Watson & Crick used the X-ray diffraction (crystallography photos) pictures obtained by Franklin of the DNA. Watson & Crick created the double helix DNA model using clue's from Franklin's work.

    Biology: Exploring Life CH:11.2

  7. Lorenzo Baroni p.2January 3, 2012 at 6:37 PM

    Watson and Crick's early models failed to explain DNA's chemical properties. Watson then observed one ofFranklin's X-ray crystallography photos of DNA. They used the clues that were provided by Franklin's work. They were able to create a new model in which two stands of nucleotides wound about each other. This shape was later called a double helix. Their model placed the sugar phosphate backbone's on the outer part of the double helix and the nitrogenous base on the inside. They hypothesized that the nitrogenous basis that crossed the two strands formed hydrogen bonds. This new model successfully
    represented DNA's structure.

    Exploring life Biology textbook chapter 11 section 2


    Rosalind Franklin's contribution to Watson and Crick's theory was her discovery that DNA is made of two strands instead of the previously believed three. She called the strands A and B since the had different patterns. Using the crystallographic theory and chemical reasoning she discovered basic facts about the structure of DNA.

    Biology; Chapter11; Section 2

  9. "Rosalind Franklin. Franklin was responsible for much of the research and discovery work that led to the understanding of the structure of deoxyribonucleic acid, DNA. Between 1951 and 1953 Rosalind Franklin came very close to solving the DNA structure. She was beaten to publication by Crick and Watson in part because of the friction between Wilkins and herself. A debate about the amount of credit due to Franklin continues. What is clear is that she did have a meaningful role in learning the structure of DNA and that she was a scientist of the first rank."