page_title: Nucleic acid secondary structure
section_title: Secondary structure motifs
hierarchical_section_title: Nucleic acid secondary structure / Secondary structure motifs
caption_attribution_description: Deutsch: Von links nach rechts: Strukturmodelle der A-, B- und Z-DNA mit jeweils 12 Basenpaaren. English: From left to right, the structures of A-, B- and Z-DNA. The structure a DNA molecule depends on its environment. In aqueous enviromnents, including the majority of DNA in a cell, B-DNA is the most common structure. The A-DNA structure is dominates in dehydrated samples and is similar to the double-stranded RNA and DNA/RNA hybrids. Z-DNA is a rarer structure found in DNA bound to certain proteins.
context_page_description: Nucleic acid secondary structure is the basepairing interactions within a single nucleic acid polymer or between two polymers. It can be represented as a list of bases which are paired in a nucleic acid molecule.
  The secondary structures of biological DNA's and RNA's tend to be different: biological DNA mostly exists as fully base paired double helices, while biological RNA is single stranded and often forms complex and intricate base-pairing interactions due to its increased ability to form hydrogen bonds stemming from the extra hydroxyl group in the ribose sugar.
  In a non-biological context, secondary structure is a vital consideration in the nucleic acid design of nucleic acid structures for DNA nanotechnology and DNA computing, since the pattern of basepairing ultimately determines the overall structure of the molecules.
context_section_description: Nucleic acid secondary structure is generally divided into helices (contiguous base pairs), and various kinds of loops (unpaired nucleotides surrounded by helices).  Frequently these elements, or combinations of them, are further classified into additional categories including, for example, tetraloops, pseudoknots, and stem-loops.
caption: The main nucleic acid helix structures (A-, B- and Z-form)
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