The amino acid sequences present in normal and sickle cell haemoglobin are shown here. normal haemoglobin sequence: thr-pro-glu sickle cell haemoglobin sequence: thr-pro-val-glu The possible mRNA codons for these amino acids are listed below. glutamic acid (glu): GAA, GAG proline (pro): CCU, CCC threonine (thr): ACU, ACC valine (val): GUA, GUG Which tRNA molecule does not take part in producing this section of the sickle cell haemoglobin?