NEET BIOLOGY

Detailed explanation-1: -People develop sickle-cell disease, a condition in which the red blood cells are abnormally shaped, if they inherit two faulty copies of the gene for the oxygen-carrying protein haemoglobin. The faulty gene persists because even carrying one copy of it confers some resistance to malaria.

Detailed explanation-2: -Sickle cell disease (SCD) is a genetic disorder caused by a mutation in both copies of a person’s HBB gene. This gene encodes a component of hemoglobin, the oxygen-carrying protein in red blood cells. The mutation causes hemoglobin molecules to stick together, creating sickle-shaped red blood cells.

Detailed explanation-3: -The sickle cell mutation is relevant to malaria because infection of a red blood cell with the malaria parasite leads to hypoxia. In individuals of the AS genotype such blood cells sickle and are then eliminated by macrophage cells of the body’s immune system, lessening the burden of infection (Luzzatto, 2012).

Detailed explanation-4: -The sickle-cell allele is widely known as a variant that causes red blood cells to be deformed into a sickle shape when deoxygenated in AS heterozygotes, in which A indicates the non-mutant form of the -globin gene, and also provides resistance to malaria in AS heterozygotes.

Detailed explanation-5: -Sickle cell disease is caused by a mutation in the hemoglobin-Beta gene found on chromosome 11. Hemoglobin transports oxygen from the lungs to other parts of the body.