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.
ON QUIZ: Bases are changed, fill in the corresponding mRNA, tRNA, and letter in the blanks below for the mutated DNA strip. Normal DNA: G. mRNA: C. tRNA: G. Mutated DNA: T. mRNA: A. tRNA: U The point mutation only changes one base out of the whole DNA so it doesn't usually change or is effected greatly.