Explain why individuals with type O blood can donate to any other blood type, and why individuals with type AB blood can accept blood of any blood type

Question

What will be an ideal response?

Answer 1

ABO blood types are determined by a gene I (I for isoagglutinin) encoding an enzyme that alters a cell-surface protein. This gene has three alleles, IA, IB, and iO—often written as A, B, and i. The dominant A and B alleles each produce a slightly different version of the enzyme, and the recessive i allele produces no enzyme. People with type A blood have A antigens on their red blood cells and do not produce antibodies against this cell-surface marker. However, people with type A blood do make antibodies against the antigen encoded by the B allele. Those with type B blood carry the B antigen on their red cells and make antibodies against the A antigen. If you have type AB blood, both A and B antigens are present on your red blood cells and no antibodies against A and B are made. If you have type O blood, you have neither antigen but do make antibodies against both the A antigen and the B antigen. Because AB individuals carry no antibodies against A or B, they can receive a
transfusion of blood of any type. Type O individuals have neither antigen and can donate blood to anyone, even though their plasma contains antibodies against A and B; after transfusion, the concentration of these antibodies is too low to cause problems.