Question

PLEASE HELP ME!!!! This figure shows two alleles for the beta-globin gene. The A allele is the most common allele. The S allele is responsible for Sickle Cell Disease. The R group glutamic acid is negatively charged, while the R group of valine is hydrophobic. What molecular change, ultimately resulting in the sickle cell phenotype, occurs when valine in substituted in place of glutamic acid at position 6 in the β subunit of hemoglobin?

Answer 1

Answer:

The correct answer is option B. The tertiary structure of the beta subunit changes, exposing a hydrophobic cleft which allows hemoglobin to form long chains in RBC.

Explanation:

As it is clearly mention as there is point mutation that leads to single nucleotide change which results in to valine instead of glutamate. Valine is hydrophobic in nature not like glutamate. Valine aggregate and makes a rigid structure of molecules.

Due to this rigid molecule of valine aggregates, RBCs form a crescent or sickle like shape due to the higher viscosity and low solubility of Mutated hemoglobin in deoxy condition. It leads to formation of polymer that blocks the vessels.

Thus, the correct answer is option B.