Sickle cell anaemia results due to mutation caused by

Options

A. Substitution
B. Insertion
C. Deletion
D. Duplication

Answer

**Step-by-Step Solution:**

1. **Understanding Sickle Cell Anemia**: Sickle cell anemia is an inherited genetic disorder that affects the shape and function of red blood cells (RBCs). In healthy individuals, RBCs are typically round and flexible, allowing them to move easily through blood vessels.

2. **Identifying the Cause**: The disorder is caused by a specific type of mutation known as a point mutation. This mutation involves a change in a single nucleotide in the DNA sequence.

3. **Locating the Mutation**: The point mutation occurs at the sixth position of the beta-globin chain of hemoglobin.

4. **Describing the Mutation**: In sickle cell anemia, the nucleotide sequence changes from GAG to GTG. This means that the original codon (GAG) which codes for the amino acid glutamic acid is replaced by the codon (GTG) which codes for the amino acid valine.

5. **Classifying the Mutation**: This change is classified as a substitution mutation because one nucleotide is replaced by another. Specifically, it is a transversion mutation because a purine (adenine) is replaced by a pyrimidine (thymine).

6. **Consequences of the Mutation**: The substitution of glutamic acid with valine leads to the production of abnormal hemoglobin, which causes the red blood cells to become sickle-shaped. These sickle-shaped cells have a reduced ability to carry oxygen and can lead to various health complications.

7. **Conclusion**: Therefore, sickle cell anemia results due to a mutation caused by substitution.

**Final Answer**: Sickle cell anemia results due to mutation caused by substitution.

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