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.
Point mutations can be subdivided into three types: 1) Nonsense mutations are the ones which code for the same amino acid. 2) Missense mutations occur in the genes which code for different amino acid. 3) Silent mutations do not affect the function of the proteins and code for different or same amino acid.