Blood transfusions in humans were risky procedures until the discovery of the major human blood groups by Karl Landsteiner, an Austrian biologist and physician, in 1900. Until that point, physicians d...Blood transfusions in humans were risky procedures until the discovery of the major human blood groups by Karl Landsteiner, an Austrian biologist and physician, in 1900. Until that point, physicians did not understand that death sometimes followed blood transfusions, when the type of donor blood infused into the patient was incompatible with the patient’s own blood. Blood groups are determined by the presence or absence of specific marker molecules on the plasma membranes of erythrocytes.
If an organism growing on the plate produces beta (β) hemolysins, the RBCs are completely destroyed or lysed and the medium surrounding the growth loses its opacity. If the blood cell membranes are pa...If an organism growing on the plate produces beta (β) hemolysins, the RBCs are completely destroyed or lysed and the medium surrounding the growth loses its opacity. If the blood cell membranes are partially lysed by the exotoxin, the RBC contents will leak out without the complete destruction of the blood cell. The hemoglobin from the RBC will be reduced to methemoglobin resulting in a green or brown discoloration to the medium surrounding the colony (Buxton, 2005).
