Question

Sickle cell anemia is caused by substitution of Glutamic Acid by which amino acid?

• A. Lysine (Lys)
• B. Methionine (Met)
• C. Valine (Val)
• D. Serine (Ser)

Hint:

In sickle cell anemia, Glutamic Acid is replaced by Valine at the 6th position of the beta-globin chain of hemoglobin, leading to sickling of RBCs.

Answer 1

The Correct Option is C

Step 1: Understanding sickle cell anemia.
Sickle cell anemia is a genetic disorder caused by a mutation in the gene coding for the beta chain of hemoglobin. This leads to defective hemoglobin known as HbS.

Step 2: Mutation involved.
In sickle cell anemia, at the sixth position of the beta-globin chain, the amino acid Glutamic Acid (hydrophilic) is replaced by Valine (hydrophobic). This substitution changes the structure of hemoglobin molecules.

Step 3: Effect of substitution.
Due to this substitution, hemoglobin molecules polymerize under low oxygen conditions, causing red blood cells to assume a sickle shape. This leads to anemia and other complications.

Step 4: Conclusion.
The correct answer is (C) Valine, as Glutamic Acid is replaced by Valine in sickle cell anemia.