Question

The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. in comparing the normal β chain with the β chain in sickle cell hemoglobin, what alteration is one likely to find?

Answer 1

Out of the following given choices;

a.            Valine instead of glutamic acid in the sixth position

b.            Glutamic acid replacing valine in the first position

c.             Extensive amino acid substitutions

d.            Trinucleotide repeats

e.            Frameshift substitutions

The answer is A. this is caused by a mutation in the beta thalassemia genes on one of the 46 human chromosomes (chromosome #11) of the individual. The alpha subunit is normal in people with sickle cell disease. When sickle hemoglobin releases oxygen in the peripheral tissues, the molecules tend to stick together and form long chains or polymers. These rigid polymers distort the cell and cause it to bend out of shape from the normative disc shape.