dactylospasm; Dactylosporangium aurantiacum subsp. hamdenesis; dactylozooid; dactylus-dactyly; Dad; daddy-long-legs; DADH; DADMS; DAF; DAF16; daffodil; Daffyâs Elixer; Dafilon; DAFNE; daft lamb; DAG; dagga; Dagger Sign; dagging; Dagnini; Dagnini, Giuseppe; Dagnini, Guido; dags; DAGU; DAH
These are comprised of 20 unique amino acids, and each is coded for by a stretch of DNA known as a codon. Codons are always 3 base-pairs (nucleotides) in length. DNA is made of 4 unique nucleotides; (A)denine, (G)uanine, (C)ytosine and (T)hymine. This means that there are 64 unique codons that can be made with these 4 bases (4*4*4). If codons were only 2 bases in length then the variety of codons that could be created would be less (only 16 unique sequences if there are still 4 nucleotides). More unique nucleotides would be required to get enough unique sequences to code for the 20 amino acids (as well as the STOP codons).
A codon is a set of three nucleotides, a triplet that code for a certain amino acid. The first codon establishes the reading frame, whereby a new codon begins.