Answer:
Sickle cell anemia refers to a recessive inheritance disorder, in which every individual carries two copies of a gene. In normal individuals, both the copies of the globin gene are normal, and they generate 2 and 4 kb fragments of DNA on digestion by BseR1. A patient with sickle cell anemia is homozygous for the recessive gene and exhibits a mutation in both the copies of a globin gene.
Therefore, BseR1 could not digest the globin gene and generate a single 6Kb fragment of DNA. In a patient acting as a carrier, one copy of a globin gene is mutated and the other is normal. As a consequence, BseR1 digestion generates 6kb of the fragment of DNA (mutated copy) and 4 and 2 kb from the normal copy of a gene.
