Question

Watson and Crick $(1953)$ proposed $DNA$ double helix model and won the Nobel Prize; their model of $DNA$ was based on (i) $X$-ray diffraction studies of $DNA$ done by Wilkins and Franklin (ii) Chargaff's base equivalence rule (iii) Griffith's transformation experiment (iv) Meselson and Stahl's experiment.

• A. (i), (ii) and (iv)
• B. (i) and (ii)
• C. (iii) and (iv)
• D. (i), (ii), (iii) and (iv)

Answer 1

Answer: (B)

(i) and (ii)

Answer 2

In $1953$, James Watson and Francis Crick based on the $X$-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin, proposed double helix model for the structure of $DNA$. One of the hallmarks of their proposition was base pairing between the two strands of polynucleotide chains. However, this proposition was also based on the observation of Erwin Chargaff ($1950$) that for a double stranded $DNA$, the ratios between Adenine and Thymine, and Guanine and Cytosine are constant and equals one.