| Summary: | The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of nucleotides that comprise the molecule. This sequence is written as a succession of letters representing a real or hypothetical nucleic acid molecule or strand. By convention, the primary structure of a DNA or RNA molecule is reported from the 5' end to the 3' end. The sequence has capacity to represent information. Biological DNA represents the information which directs the functions of a living thing. In that context, the term genetic sequence is often used. Sequences can be read from the biological raw material through DNA sequencing methods. Nucleic acids also have a secondary structure and tertiary structure. Primary structure is sometimes mistakenly referred to as primary sequence. Conversely, there is no parallel concept of secondary or tertiary sequence.
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