DNA) is a molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses.
DNA and RNA are nucleic acids; alongside proteins, lipids and complex carbohydrates (polysaccharides), they are one of the four major types of macromolecules that are essential for all known forms of life.
The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone.
The nitrogenous bases of the two separate polynucleotide strands are bound together (according to base pairing rules (A with T, and C with G) with hydrogen bonds to make double-stranded DNA.
The total amount of related DNA base pairs on Earth is estimated at 5.0 x 10 DNA stores biological information.
Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix.
The two DNA strands are termed polynucleotides since they are composed of simpler monomer units called nucleotides.
Attached to each sugar is one of four types of nucleobases (informally, bases).
It is the sequence of these four nucleobases along the backbone that encodes biological information.
The DNA backbone is resistant to cleavage, and both strands of the double-stranded structure store the same biological information.
This information is replicated as and when the two strands separate.