In sickle cell anaemia, the glutamic acid is replaced by

Options

A. proline
B. valine
C. nine
D. alanine

Answer

### Step-by-Step Solution:

1. **Understanding Sickle Cell Anemia**:
- Sickle cell anemia is a genetic disorder that affects the shape of red blood cells. Normally, red blood cells are bi-concave discs, which allow them to move easily through blood vessels.

2. **Identifying the Mutation**:
- In sickle cell anemia, there is a specific mutation in the hemoglobin gene. This mutation leads to the replacement of one amino acid in the hemoglobin protein.

3. **Amino Acid Replacement**:
- The amino acid glutamic acid (which is normally present in hemoglobin) is replaced by another amino acid. In the case of sickle cell anemia, glutamic acid is replaced by **valine**.

4. **Consequences of the Mutation**:
- This single amino acid change from glutamic acid to valine causes the hemoglobin molecules to stick together under low oxygen conditions, leading to the distortion of red blood cells into a sickle shape.

5. **Genetic Basis**:
- Sickle cell anemia is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to express the disease.

### Final Answer:
In sickle cell anemia, glutamic acid is replaced by **valine**.

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