2023 Manipur Principles of Inheritance and VariationMolecular basis of sickle cell anaemia Medium Question 36 of 198 in Principles of Inheritance and Variation

Select the correct statements about sickle cell anaemia. (A) There is a change in gene for beta globin. (B) In the beta globin, there is valine in the place of Lysine. (C) It is an example of point mutation. (D) In the normal gene U is replaced by A. Choose the correct answer from the options given below:

A (B), (C) and (D) only
B (B) and (D) only
C (A), (B) and (D) only
D (A) and (C) only

The answer is D.

Solution

Sickle cell anaemia results from a mutation in the gene for the beta chain of haemoglobin (A is correct), and this substitution is a classic example of a point mutation (C is correct). However, the actual substitution is valine replacing glutamic acid (not lysine, so B is incorrect), and it is the DNA base (not simply 'A' replacing 'U', which is an RNA-level statement rather than the correct DNA-level base change) — so D as stated does not correctly represent the mutation. Correct: A and C only.

Concept Molecular basis of sickle cell anaemia

Principles of Inheritance and Variation in past papers

198 questions from this chapter have appeared across 27 exam years.