Question

Given below is the representation of amino acid composition of the relevant translated portion of β-chain of haemoglobin, related to the shape of human red blood cells.

1. Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
2. What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
3. Who are likely to suffer more from the defect related to the gene represented the males, the females or both males and females equally? And why?

Answer 1

1. The red blood cells are from a normal human being.
2. Under conditions of low oxygen levels, the mutant hemoglobin molecules tend to polymerize. This causes the red blood cells to change their shape from the typical biconcave disc to an elongated, sickle-like form, a characteristic of sickle-cell anemia.
3. Both males and females are equally affected because the trait is inherited as an autosomal recessive gene, meaning it is present on non-sex chromosomes and requires two copies for the condition to manifest.