What is an Open Reading Frame (ORF)?

An Open Reading Frame (ORF) is a continuous stretch of DNA sequence that begins with a start codon (usually ATG) and ends with a stop codon (TAA, TAG, or TGA), potentially encoding a protein. A single DNA sequence has six possible reading frames (three on each strand), and bioinformatics tools identify ORFs to predict potential genes. Key considerations include: minimum length requirements (typically >100 codons for significance), presence of regulatory elements like promoters and ribosome binding sites, and codon usage bias. ORF identification is a fundamental step in genome annotation and gene prediction.