Principles of Inheritance and Variation Question 160
160. Sickle cell anaemia is:
[2009]
(a) caused by substitution of valine by glutamic acid in the beta globin chain of haemoglobin
(b) caused by a change in a single base pair of DNA
(c) characterized by elongated sickle like $RBCs$ with a nucleus
(d) an autosomal linked dominant trait
Show Answer
Answer : b
Hints & Solution
(b) Sickle cell anaemia is caused by a change in a single base pair of DNA. Sickle cell anaemia is controlled by a single pair of alleles, $Hb^{A}$ and $Hb^{S}$ and the genotype $Hb^{S} . Hb^{S}$ show the diseased phenotype. Sickle cell disease or sickle cell anaemia (or drepanocytosis), is a life-long blood disorder characterised by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells flexibility and results in a risk of various complications.
