Question

Choose the correct answer from the alternatives given:
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

Hint: J.D. Watson and F.H.C. Crick (1953) merged physical and chemical data and suggested a double helix model for DNA molecules. This model has been generally accepted. The DNA molecule consists of two strands, according to this model, that are bound together by hydrogen bonds and helically twisted.

Complete Answer:
- DNA, the molecule that is the basis of inheritance, includes the patterns of the body's protein construction, including the different enzymes.
- When it was determined that DNA consists of two two chains twisted around each other, or double helixes, of alternating phosphate and sugar groups, a new understanding of heredity and genetic disease was possible and that the two chains are held together by hydrogen bonds between pairs of organic bases-adenine (A) with thymine ( T) and guanine ( G) with cytosine(C).
- A purine base nucleotide, which alternates with that of a pyrimidine base nucleotide, consists of each step on one strand. A strand of DNA molecule is therefore a polymer of four nucleotides, i.e. A, G, T, C. To form a double helix, the two strands are connected together. Bases of two nucleotides are formed by hydrogen bonds, i.e. A combines two hydrogen bonds with T (A = T) and G combines three hydrogen bonds with C (G = C).
- Erwin Chargaff was one of a handful of scientists who built on the work of Levene by uncovering more knowledge of the DNA structure, paving the way for Watson and Crick more.
- The discovery by Chargaff that A = T and C = G, together with some crucially significant X-ray crystallography work by English researchers Rosalind Franklin and Maurice Wilkins, led to the derivation of the three-dimensional, double-helical model for the DNA structure by Watson and Crick.

The correct answer is option (B) I AND II.

Note: In 2005, the Chemical Heritage Foundation, now the Science History Institute, awarded James Watson with the Othmer Gold Medal for his scientific skills, which have brought the world a new intellectual understanding of the essence of life , allowing modern biotechnology and a better life for all humanity.