Question

The correct structure of DNA components can be presented as:a. phosphate–base–sugar. b. phosphate–sugar–base. c. base–phosphate–sugar. d. phosphate–sugar–phosphate–base. e. base–sugar–phosphate–base.

Answer 1

Answer:

. b. phosphate–sugar–base.

Explanation:

DNA is made up of  Phosphate group

, a Ribose sugar Nitrogenous bases

The  sequence of arrangement is such that there is alternating group of  phosphate and Ribose sugar (forming the backbone)  with the base projecting outwards.  This arrangements is called  polynucleotides. Phosphate groups  bonded with ribose sugar at C5 and C3  by covalent bond (phosphodiester bonds) to give 3' and 5' ends. Nitrogenous bases are bonded directly  by N-glycosidic bond to ribose sugar.

The above  sequence of arrangement  also occur in adjacent polynucleotide but in opposite direction.  Therefore  two strands are held together by hydrogen bonds, between  the bases ;purines and pyrimidine, to form  double strands.They  are arranged in anti parallel position to from  complimentary bases pairs.