Final answer:
Glycosylation determines blood type by adding specific monosaccharides to oligosaccharides on red blood cell surfaces, such as N-acetylgalactosamine for type A, which dictates immunity reactions during transfusions.
Step-by-step explanation:
Glycosylation plays a pivotal role in the specification of blood types within the ABO system. In individuals with blood type A, an enzyme adds a monosaccharide, specifically N-acetylgalactosamine, to the oligosaccharide on the surface of red blood cells. This modified oligosaccharide becomes antigen A, which is recognized by the immune system as type A blood. In contrast, blood type O lacks these additional sugar modifications and therefore does not express the antigens A or B, making it the universal donor. Blood type compatibility is crucial during transfusions because if a person receives blood with unfamiliar antigens, their immune system may react against the donated blood cells, leading to complications such as agglutination or kidney failure.
The antigen-antibody model explains the immune response to foreign antigens in the blood. Individuals with blood type AB have both A and B antigens on their red blood cells and lack anti-A and anti-B antibodies, thereby increasing their susceptibility during transfusions only if they receive blood containing non-ABO compatible antibodies.