DNA (deoxyribonucleic acid) is the long polymeric macromolecule of nucleotides containing codes inscribed in the form of biochemical molecules which serve as both the developmental and hereditary unit of living organisms.

ScienceDaily defines DNA (Deoxyribonucleic acid) as a nucleic acid that contains the genetic instructions for the development and function of living things. All known cellular life and some viruses contain DNA.

Nucleotides comprise a five-carbon sugar (deoxyribose), a nitrogenous base (Adenine, Guanine, Thymine or Cytosine).

The polymeric structure of DNA is constructed of successive nucleotides linked by phosphodiester bonds (bond formed by linkage of 3-carbon and 5-carbon by a phosphate).

The double strand of DNA is formed by Hydrogen bonding between the complementary nitrogenous bases.

DNA in higher animals is present in the form of supercoiled structures called the chromosomes, which is contained inside the nucleus of the eukaryotic cell.

In its physiological state, DNA exists in a nucleoprotein complex containing roughly equal amounts of histones and DNA, which interacts with nuclear matrix proteins for stability and folding.

This complex is folded into a basic structure termed a nucleosome containing approximately 150 base pairs. Nucleosome undergoes further coiling to form a chromosome.

During replication, transcription, splicing, nick formation, and other complex processes, the DNA in coiled form is unwinded and reminded.

Prokaryotic organisms like bacteria have coiled DNA in their cytoplasm present in a nucleoid region. They lack a membrane-bound nucleus.

The haploid human genomic DNA contains 3×10^9 nucleotides.

The DNA contains the code that is transcribed by the cell to build proteins, and constitutively an entire living organism. Hence, it is also called the blueprint of life.

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