The disease sickle-cell anaemia is caused by the substitution of `overset("(i)") "____"` by `overset("(ii)") "____"` at the `overset("(iii)") "____"` position of `overset("(iv)") "____"` globin chain of haemoglobin molecule
Which of the following correctly fills the blanks in the above statements ?

Options

A. (i) valine, (ii) glutamic acid, (iii) sixth, (iv) beta
B. (i) glutamic acid, (ii) valine, (iii) sixth, (iv) beta
C. (i) glutamic acid, (ii) valine, (iii) fifth, (iv) beta
D. (i) valine,(ii) glutamic acid, (iii) fifth, (iv) beta

Answer

To solve the question regarding sickle-cell anaemia and the specific substitutions in the hemoglobin molecule, we can break it down step-by-step:

### Step-by-Step Solution:

1. **Understanding Sickle-Cell Anaemia**:
- Sickle-cell anaemia is a genetic disorder that affects the shape of red blood cells, causing them to become sickle-shaped instead of the normal disc shape. This affects their ability to carry oxygen efficiently.

2. **Identifying the Cause**:
- The disease is caused by a specific mutation in the hemoglobin molecule. Hemoglobin is made up of globin chains, and in sickle-cell anaemia, there is a substitution of one amino acid for another.

3. **Substitution of Amino Acids**:
- The specific amino acid substitution that causes sickle-cell anaemia is the replacement of glutamic acid (an amino acid) with valine (another amino acid).

4. **Position of the Substitution**:
- This substitution occurs at the sixth position of the beta globin chain of the hemoglobin molecule.

5. **Filling in the Blanks**:
- Therefore, the correct filling of the blanks in the statement is:
- (i) "glutamic acid"
- (ii) "valine"
- (iii) "6th"
- (iv) "beta"

### Final Statement:
The disease sickle-cell anaemia is caused by the substitution of **glutamic acid** by **valine** at the **6th** position of **beta** globin chain of hemoglobin molecule.