Biosequence

Biosequence refers to the sequence of biological monomers in a biopolymer, most commonly the order of nucleotides in DNA or RNA or the order of amino acids in a protein. The arrangement encodes genetic information and largely determines molecular structure and function. In bioinformatics, sequences are represented as strings over alphabets: A, C, G, T (and U for RNA) for nucleotides, and the 20 standard letters for amino acids. Sequences can be linear or circular and may include exons, introns, and regulatory elements within genomic DNA.

Types and formats: DNA, RNA, and proteins form primary structures. Sequences are stored in standard formats, notably FASTA for simple sequence data and FASTQ for reads with quality scores. Sequences are associated with identifiers, annotations, and metadata that describe provenance and features.

Analysis and applications: Common tasks include sequence alignment (global and local), motif and domain identification, gene prediction, and phylogenetic analysis. Algorithms and tools enable comparative genomics, functional annotation, and structure or interaction prediction. Biosequences underpin activities in medicine, agriculture, and biotechnology, including variant interpretation, primer design, genome editing, and synthetic biology.

Data resources and standards: Public repositories such as GenBank, EMBL, and DDBJ provide large collections of biosequences and annotations, often mirrored across centers. UniProt offers curated protein sequences and functional information. Standardization of formats, identifiers, and metadata supports interoperability and reproducibility across research disciplines.