Deoxyribonucleic acid ( DNA)

Deoxyribonucleic acid contains the genetic instructions used in the development and functioning of an organisms.It’s is used for the long-term storage of information .Chemically, DNA is a long polymer of simple units called nucleotides, with a backbone made of sugars and phosphate atoms joined by ester bonds. sugar attached to one of four types of bases. Sequence of these four bases along the backbone encodes information which read in triplet ( genetic code).This trplet specifies the sequence of the amino acids within proteins. Stretches of DNA has been copying into RNA i.e. transcription. Most of these RNA molecules are used to synthesize proteins i.e translation

DNA is organized into structures called chromosomes within cells and the set of chromosomes make up a genome. Eukaryotes store their DNA inside the cell nucles, while in prokaryotes it is found in the cell's cytoplasm. DNA usually exist as a tightly-associated pair of molecules. These two long strands entwine like vines, in the shape of a double helix. The double helix has folloeing features-
1.It contains two polynucleotide strands wound around each other and The two strands are "antiparallel” means direction of the nucleotides in one strand is opposite to their direction in the other strand. . The asymmetric ends of a strand of DNA bases are referred to as the 5′ (five prime) and 3′(three prime) ends
2.The backbone of each consists of alternating deoxyribose and phosphate groups. The phosphate group bonded to the 5' carbon atom of one deoxyribose is covalently bonded to the 3' carbon of the next.
3.The purine or pyrimidine attached to each deoxyribose projects in toward the axis of the helix.
Each base forms hydrogen bonds with the one directly opposite it, forming base pairs (also called nucleotide pairs).
5. 3.4 Å separates the planes in which adjacent base pairs are located.
The double helix makes a complete turn in just over 10 nucleotide pairs, so each turn takes a little more (35.7 Å to be exact) than the 34 Å shown in the diagram. The diameter of the helix is 20 Å.
6.The path taken by the two backbones forms a major (wider) groove (from "34 A" to the top of the arrow) and a minor (narrower) groove (the one below).