Question

Perform a cross between two sickle cell carriers. What ratio is obtained between carrier, disease free and diseased individuals in F₁ progeny? Name the nitrogenous base substituted, in the haemoglobin molecule in this disease.

Answer 1

Sickle cell anemia is not associated with sex chromosomes and is an autosomal recessive condition that requires two copies of the Hb^S gene to appear.

Sickle Cell Carrier Cross and F₁ Ratio: 

• Carrier: 50%, Disease-free: 25%, Diseased individuals: 25%
• Ratio: 2 : 1 : 1

Mutation in Sickle Cell Anaemia: At the sixth codon of the B-globin gene, glutamic acid (GAG) is substituted with valine (GUQ). This results in sickle-shaped RBCs, which impair oxygen delivery.