Question

Double helix model of DNA was proposed by

• A. Nirenberg
• B. Komberg
• C. Holley and Nirenberg
• D. Watson and Crick

Answer 1

Answer: (D)

Watson and Crick

Watson and Crick suggested the double helix model of DNA. He stated that DNA is made up of two strands that twist around each other to form a right-handed DNA. The two DNA strands are anti-parallel. The backbone of DNA is made up of sugar and phosphate. There are approximately 10 nitrogenous bases per turn in DNA. It has major grooves and minor grooves. Nitrogenous bases ad purine and pyrimidine. Purines are adenine (A) and cytosine (C). Pyrimidines are Thymine (T) and guanine (G). In DNA, there are two hydrogen bonds between adenine (A) and thymine (T) and three hydrogen bonds between cytosine (C) and guanine (G). These are called as complementary base pairs.

Thus, the correct answer is option D.