Question

Sickle-cell disease is caused by a single base pair substitution in the gene for the beta globin subunit of hemoglobin. This base substitution changes one of the amino acids in the hemoglobin molecule from glutamic acid to valine. Look up the structures of glutamic acid (glu) and valine (val). (Google this online or use your textbook.) What is the chemical property of each side chain (R group)?

Answer 1

Explanation:

Sickle cell anemia is a disease that is caused by the sickle shape of the oxygen carrier molecule called hemoglobin in the blood. The hemoglobin since is a protein, therefore, is composed of the amino acids and it is the 3 D arrangement of these amino acids which provides proteins its function.

The amino acids are coded by the DNA present in the molecule therefore the shape is the result of the DNA.  The mutation in the DNA causes the substitution of the glutamic acid to valine at 6th position.

The glutamic acid contains -COOH group in its R side chain which becomes C00- as a result of which the amino acid is negative and acidic in nature. This negative charge allows the formation of bonds with positive change which stabilizes the structure of the protein.

Valine is a neutral and non-polar amino acid therefore will not form any bond with the proteins and thus a stable structure is not formed.  This difference in the side chain in the amino acids is the region the hemoglobin structure is changed.