Question

Hemoglobin is a protein in the blood that is made of 4 polypeptide chains. Two alpha chains are composed of 141 amino acids each Two beta chains are 146 amino acids long. There a total of 574 amino acids in a hemoglobin molecule.

People with sickle cell anemia have one incorrect amino acid in their beta chain. The first seven amino acids in the beta chain for hemoglobin A (normal) and hemoglobin S (sickle cell) are listed below. Which amino acid is different in hemoglobin S?

Hemoglobin A: valine histidine leucine threonine proline glutamine glutamine

Hemoglobin S: valine histidine leucine threonine proline valine glutamine

Why does the body produce hemoglobin S instead of hemoglobin A?



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Answer 1

Amino acid differs at the glutamine, which is converted to valine in hemoglobin S. the body produced hemoglobin S due to a point mutation in the DNA sequence which results in different amino acid to be formed during translation of DNA sequence codons.