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'''Deoxyribonucleic acid''' ('''DNA''') is a [[nucleic acid]] that contains the [[genetics|genetic]] instructions used in the development and functioning of all known living [[organism]]s and some [[virus]]es. The main role of DNA [[molecule]]s is the long-term storage of [[information]]. DNA is often compared to a set of [[blueprint]]s or a recipe, or a [[code]], since it contains the instructions needed to construct other components of [[cell (biology)|cells]], such as [[protein]]s and [[RNA]] molecules. The DNA segments that carry this genetic information are called [[gene]]s, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.
Chemically, DNA consists of two long [[polymers]] of simple units called [[nucleotide]]s, with backbones made of [[sugar]]s and [[phosphate]] groups joined by [[ester]] bonds. These two strands run in opposite directions to each other and are therefore [[antiparallel (biochemistry)|anti-parallel]]. Attached to each sugar is one of four types of molecules called [[nucleobase|bases]]. It is the primary sequence of these four bases along the
Within cells, DNA is organized into structures called [[chromosome]]s. These chromosomes are duplicated before cells [[cell division|divide]], in a process called [[DNA replication]]. [[Eukaryote|Eukaryotic organisms]] ([[animal]]s, [[plant]]s, [[Fungus|fungi]], and [[protist]]s) store their DNA inside the [[cell nucleus]], while in [[prokaryote]]s ([[bacteria]] and [[archaea]]) it is found in the cell's [[cytoplasm]]. Within the chromosomes, [[chromatin]] proteins such as [[histone]]s compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.
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