question_answer

The double helix of DNA is made of polynucleotide chains where in backbone constituted by sugar phosphate and the bases are projected

A)  inside

B)  outside

C)  one base inside and the other outside

D)  bases remain-in line of sugar phosphate

Correct Answer: D

Solution :

                                 DNA a large molecule, is made up of a long chain of up to two lakhs nucleotide pairs Its molecular weight may be between 50,00000 to 9,00,00,000. Each nucleotides contain a nitrogenous base (pyrimidine or purines) a pentose sugar molecule and a phosphoric acid. Purine are adenine and guanine while pyrimidine are cytosine and thymine. Each nucleotide possess only one of the four bases. These nucleotide are attached with each other in a lever arrangement fashion through their   sugar and phosphate molecule is sugar and phosphate form the backbone of DNA double helix, while base are projected in line of- sugar phosphate.