A double-stranded nucleic acid that contains the genetic information for cell growth, division, and function.


Structure: DNA is composed of two strands that twist together to form a helix. Each strand consists of alternating phosphate (PO4) and pentose sugar (2-deoxyribose), and attached on the sugar is a nitrogenous base, which can be adenine, thymine, guanine, or cytosine. In DNA, these bases pair; adenine pairs with thymine and guanine with cytosine. Hence, DNA is a ladder-like helical structure.

Location: DNA is found in the cytoplasm of prokaryotic cells, and chiefly in the nucleus of eukaryotic cells. A small fraction of total DNA is present in mitochondria and chloroplasts.

Function: DNA is a long polymer of nucleotides to code for the sequence of amino acid during protein synthesis. DNA is said to carry the genetic ‘blueprint’ since it contains the instructions or information (called genes) needed to construct cellular components like proteins and RNA molecules.

Word origin: abbreviation of deoxyribonucleic acid.
See also: gene, base pair, genetic code, RNA.

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