Tensor tympani- The tensor tympani is the larger of the two muscles of the auditory canal, the other being stapedius. The muscle functions to dampen down sounds such as chewing. It arises from the cartilaginous portion of the eustachian tube as well as the adjacent section of the greater wing of the sphenoid bone.
A nonsense mutation in the leptin gene that results in a stop codon and lack of leptin production was first observed in mice in 1950. In the mouse gene, arginine-105 is encoded by CGA and only requires one nucleotide change to create the stop codon TGA.
The sickle cell mutation results in the substitution of the amino acid valine for glutamic acid in the sixth position of the beta polypeptide. In turn, this alters the conformation of the hemoglobin molecule and causes the red blood cells to assume a characteristic sickle shape under certain conditions.he sickle cell mutation results in the substitution of the amino acid valine for glutamic acid in the sixth position of the beta polypeptide. In turn, this alters the conformation of the hemoglobin molecule and causes the red blood cells to assume a characteristic sickle shape under certain conditions.