Final answer:
Blood type O is characterized by the absence of antigens A and B, making individuals with this type universal donors. Blood type AB individuals have both antigens, classifying them as universal recipients. The genotypes for these types are OO for O and AB for AB.
Step-by-step explanation:
Characteristics of Blood Types O and AB
The ABO blood types are determined by the presence or absence of certain antigens on the surface of red blood cells. Blood type O is characterized by the absence of both A and B antigens on the erythrocytes, and thus people with this blood type have neither of these antigens. Those with blood type O are considered universal donors because their blood can be given to individuals with any ABO blood type without causing an immune reaction due to ABO incompatibilities.
Blood type AB individuals have both antigens A and B on their erythrocytes, making them universal recipients because they can receive red blood cells from any ABO type without suffering from an immune reaction due to ABO incompatibilities. The genotype for a person with blood type A can be either AA or AO, while the genotype for a person with blood type B can be either BB or BO. For blood type AB, the only possible genotype is AB, and for blood type O, it is OO.