Question

The diagram below shows the sequence of amino acids in part of a haemoglobin molecule.

Key:

Val = valine His = histidine Leu = leucine

Thr = threonine Pro: proline Glu = glutamic acid

1. If the base T* was substituted with A, how would it affect the haemoglobin chain?
2. Name the condition and the effects associated with the above substitution.

Answer 1

1. CTT would become CAT which codes for valine. Thus, valine would replace glutamic acid at that point.
2. In sickle cell anaemia, the mutant haemoglobin molecule undergoes polymerization leading to the change in the shape of the RBC from a biconcave disc to an elongated sickle-like structure.