A group of polymers made of repeating units of phosphoric acid and sugar to which nucleotide bases are attached. The two most commonexamples are DNA and RNA.
In most living organisms, genetic information is stored in the molecule deoxyribonucleic acid, or DNA. DNA is madeand resides in the nucleus of living cells and gets its name from the sugar molecule contained in its backbone (deoxyribose). Four different nucleotidebases occur in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T).
The double-stranded helix DNA molecule has the unique ability that it canmake exact copies of itself, or self-replicate, so when more DNA is required by an organism (such as during reproduction or cell growth) the hydrogenbonds between the nucleotide bases break and the two single strands of DNA separate.
Ribonucleic acid, or RNA, also gets its name from the sugargroup in the molecule's backbone - ribose. Many similarities and differences exist between RNA and DNA. Like DNA, RNA has a sugar-phosphate backbonewith nucleotide bases attached to it. RNA contains the same bases as DNA except for the thymine, which is replaced by the racil(U).
RNA is the maingenetic material used in the organisms called viruses, and RNA is also important in the production of proteins in other living organisms. RNA serves asgenetic messenger, relaying the information stored in the cell's DNA out from the nucleus to other parts of the cell where it is used to help make proteins.