c) In the quest to solve the DNA structure, prominent scientist, Dr. Linus Pauli

Question

c) In the quest to solve the DNA structure, prominent scientist, Dr. Linus Pauling proposed a "triple helix" structure. This turned out to be wrong. Here is the Figure from Pauling's original paper, showing the phosphates on the inside and the bases on the outside. What are the major problems with this model based on the properties of the DNA components and Chargraff's rules? (2 pts) d) Rosalind Franklin's data was shown to Watson and Crick by Wilkins, and was the catalyst for their correct double helical model of DNA for which they would eventually win the Nobel prize. Given what you know, briefly summarize (1-2 sentences) what actions in this case may have been unethical. Do you think there should be code of ethics in science or is the price for scientific progress sometimes moral ambiguity? (3 pts)

Explanation / Answer

c. According to Chargaff’s rule, the ratio of purine: pyrimidines in DNA is 1:1. Hence, amount of guanine equal to amount of cytosine. Amount of adenine= amount of thymine. The bases are found in pairs.

The triple helix proposed by Linus Pauling, however does not follow Chargaff’s rule. DNA was proposed to be a triple helix with phosphates on inside and nitrogenous bases on outside. Phosphates are negatively charged. Large number of phosphates would therefore repel each other and the molecule will fall apart. Such DNA helix would not be possible under normal cellular conditions. If the bases were pointing outwards, they would not be involved in base pairing. Hence, the ratio of purine: pyrimidines would never be 1:1. This model also fails to explain DNA biology and DNA replication. If there are three strands, then DNA cannot be replicated by semi conservative mode and inheritance of one original strand in each daughter cell is not possible.

d. The X-ray diffraction photographs that Rosalyn Franklyn generated were submitted confidentially to Medical research Council in 1952 and no permission was given to Watson and Crick for persona use. Watson and Crick did not give credit to Rosalyn Franklyn for the evidence and image 51 in their publication, even though it was critical part of their work, making it unethical in scientific research.

Scientific research should be ethical because respects and acknowledges the work of scientist. Work of Rosalyn Franklin was very important for deciphering the double helix structure of DNA. However, this aspect was never acknowledged by Watson and Crick. Hence, she was given minimal acknowledgement for her contributions. Further, the data was fraudently acquired without her knowledge. It is unethical to cite other peoples work in research morally. Scientists spend a lot of time for research, without an aim to become rich. Acknowledgement for their work is their reward. Scientific ethical work will prevent conflict of interest and provide right information to the public.

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