Deoxiribo Nucleic acid or shortly DNA is a nucleic acid that carries the genetic instructions necessary for the viability and biological development of all organisms and some viruses. The main role of DNA is the long-term storage of knowledge. DNA, because it contains the information necessary for the construction of other components of the cell, such as protein and RNA; it is likened to a mold, template, or recipe. DNA fragments containing this genetic information are called genes. But other DNA sequences have structural functions (such as determining the shape of chromosomes), while others are useful in regulating the way in which these genetic information is used (in which cells, under which conditions).
Chemically, DNA consists of two long polymers of simple units called nucleotides. The backbones of these polymers consist of sugar and phosphate groups linked together by ester bonds. These two yarns extend in opposite directions. Each sugar group is bound to one of four types of molecules called bases. The sequence of these bases along the backbone of the DNA encodes genetic information. During protein synthesis, this information determines the amino acid sequence of proteins when read through the genetic code. During this process, the information in the DNA is copied to another nucleic acid having DNA-like structure. This process is called transcription.
In cells, DNA is located in structures called chromosomes. The chromosomes are mapped before cell division, while DNA replication occurs. In eukaryotic organisms (ie, animals, plants, fungi, and protistants) DNA is contained in the cell nucleus, prokaryotic organisms (ie bacteria and archaea) have DNA in the cell cytoplasm. Chromatin proteins in chromosomes (such as histones) compress and organize DNA. These constricted structures regulate the interactions between DNA and other proteins to control which parts of the DNA are read.