Question

The disease sickle-cell anaemia is caused by the substitution of ___(i)____ by ____(ii)____ at the ____(iii)____ position of ____(iv)_____ globin chain of the haemoglobin molecule.
Which of the following CORRECTLY fills the blanks in the above statement?

• 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 1

Answer: (B)

Sickle cell anemia is a type of genetic blood disorder which is inherited from the parents. The person suffering from it develops an abnormal haemoglobin that leads to elongated and curved or sickle shaped RBC. Such condition occurs when the individual inherits two abnormal copies of gene for beta globin chain of haemoglobin from each parent. Normally, the red pigment molecule is made of four polypeptide chains two α-chains and two $\beta$ -chains. Sickle cell anaemia results in glutamic acid (Glu) is replaced by valine (Val) at sixth position in each of two $\beta$ globin chain of haemoglobin. Such mutation is called as substitution mutation.