Index >> Gene Mutation >> Change in Only One Amino Acid Can Have a Drastic Effect on the Phenotype

Change in Only One Amino Acid Can Have a Drastic Effect on the Phenotype -

Haemoglobin, which is found in the R. B. C., is a protein molecule consisting if four chains, two alpha chains and two beta chains. These chains consist of amino acids arranged in a definite sequence.

Normal R.B.C. are disc shaped. Changes in haemoglobin structure results in certain types of anaemia called sickle cell anaemia and haemoglobin D anaemia. In sickle cell anaemia the R. B. C. become sickle shaped when oxygen tension is reduced, and are much less effective in the transportation of oxygen.

Death may occur in severe cases of sickle cell anaemia. Normal haemoglobin has the amino acid glutamic acid in the sixth position. In sickle cell haemoglobin C it is substituted by lysine.