Sickle cell anaemia is due to substitution/transversion (point mutation) in which

Options

A. instead of glutamic acid, valine comes at number 6th position in one of `beta` chain of Hb
B. instead of valine, glutanic acid is inserted at number 6th position of `beta`-chain of Hb
C. valine is inserted at number 6th position in `alpha` chain of Hb
D. glutamic acid is substituted by valine at number 6th position of `alpha`-chain of Hb

Answer

**Step-by-Step Text Solution:**

1. **Understanding Sickle Cell Anemia**: Sickle cell anemia is a genetic disorder that affects the shape of red blood cells (RBCs). In this condition, the RBCs become sickle-shaped instead of the normal disc shape.

2. **Identifying the Cause**: The primary cause of sickle cell anemia is a mutation in the hemoglobin gene. This mutation is classified as a point mutation, which involves a change in a single nucleotide.

3. **Location of the Mutation**: The mutation occurs specifically in the beta chain of hemoglobin at the sixth position of the amino acid sequence.

4. **Nature of the Mutation**: In sickle cell anemia, the normal codon for the amino acid glutamic acid (GAG) is mutated. The adenine (A) in the codon is replaced with thymine (T), resulting in a new codon (GTG) that codes for the amino acid valine instead of glutamic acid.

5. **Conclusion**: Therefore, the mutation that leads to sickle cell anemia is a substitution point mutation where glutamic acid is replaced by valine at the sixth position of the beta chain of hemoglobin.

6. **Final Answer**: The correct answer to the question is that sickle cell anemia is due to a substitution point mutation where valine replaces glutamic acid at the sixth position in the beta chain of hemoglobin.

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