Final answer:
Type O blood patients lack both antigens A and B on their erythrocytes, making them universal donors.
Step-by-step explanation:
Type O blood patients lack both antigens A and B on their erythrocytes. This means they do not have glycolipids called antigen A or antigen B on the surface of their red blood cells. Type O blood is considered the universal donor because it can be given to people with blood types A, B, AB, or O, as it does not elicit an immune response when injected into a person of any blood type.