A sestina, or sextain, is a poem comprised of six stanzas containing six lines each. These six-by-six stanzas are followed by a shorter (3-line) final stanza known as an envoi. This gives the sestina a total of 39 lines (6 * 6 + 3 = 39).
1 A nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon, or a nonsense codon in the transcribed mRNA, and possibly a truncated, and often nonfunctional protein product.
The mRNA Sequence. The sequence of mRNA is transcribed from DNA, which carries information from the synthesis of protein. In mRNA, three consecutive nucleotides encode either a stop signal for protein synthesis or an amino acid. The trinucleotide is called a âcodon.â.