BLOOD TYPE

Red blood cells have glycoproteins on their surface which act like "flags" to identify the cells. The glycoproteins are coded for by the blood type genes A, B, and O. Unlike Complete Dominance where one gene totally masks another (ie. T vs. t), the blood type genes, A and B, are Co-dominant or equally dominant. Therefore, an individual with the genotype AB will possess both A-type glycoproteins and B-type glycoproteins on their RBC's.

Antibodies are proteins made by the immune system which attack foreign matter in the body. If A-type blood enters the body, anti-A antibodies will attack it. If B-type blood enters, anti-B antibodies will attack it. If AB-type blood enters, anti-A and anti-B antibodies will attack it. If O-type blood enters, no antibodies will attack since O-type blood cells do not have the glycoproteins on the surface. The presence or absence of the different antibodies determines which blood types can be safely received during a blood transfusion.When antibodies attack blood cells they cause the cells to "clump" or "agglutinate". This agglutination can be used as a clinical test to determine what blood type a person has. This is what you will do in the lab.