The primary purpose of DNA is to store hereditary information within the cells of all living things. It is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms.
DNA also facilitates biological synthesis specifically in the creation of RNA molecules and cellular proteins.
Information stored in DNA is in the form of a code consisting of four chemical bases: adenine, guanine, cytosine and thymine. These bases pair up with each other to form base pairs. This process is known as base pairing, and it occurs when the bases attach to one another through hydrogen bonds. Each base is attached to a sugar molecule and a phosphate molecule. Collectively, a base, sugar and phosphate form a nucleotide.
Nucleotides are arranged in two biopolymer strands called polynucleotides. Polynucleotides coil around each other in a double helix, which takes a form similar to a ladder's. Nucleotides are connected to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next. This sequencing of the bases that connect the two biopolymer strands determines the natural characteristics of the living thing in which that specific DNA exists.