Question

With the help of a neat and labeled diagram describe Waston and Crick's model of DNA.

Answer 1

DNA is a double helical structure consisting of two long strands, coiled around a ventral axis. This structure was discovered by Watson and Crick. Each strand is a polynucleotide chain, composed of many nucleotides. Each is formed by a pentose, deoxyribose sugar, a phosphate group and one nitrogen base. Sugar and nitrogenous bases are connected to each other by glycosidic bond while sugar and phosphate are joined by a phosphodiester bond, known as phosphodiester linkage. There is a complementary pairing of purines and pyrimidines. Adenine, thymine pair with double. H bond, While cytosine and guanine pair with triple H bond. H bond forms the rings in DNA molecule. The total number of purines always equals to the total number of pyrimidines, that is, A+G=T+C. This is known as Chargaff's law. One strand of DNA has 3′→5′ polarity, while opposite strand has polarity 5′→′3′. The diameter of DNA is 2 nm. The distance between two successive nucleotide is 0.34 nm. There are 10 base pairs in one complete spiral turn.